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INVENTIONS OF THE 
GREAT WAR 




Oil-tempering the lining of a Big Gun (See page 76) 



INVENTIONS OF THE 
GREAT WAR 



BY 

A. RUSSELL BOND 

Managing Editor of "Scientific American- 

Author of "On the Battle-Front 

of Engineering," etc. 



WITH MANY 
ILLUSTRATIONS 




NEW YORK 
THE CENTURY CO. 

1919 






Copyright, 1918, 1919, by 
The Century Co. 



Published, June, 1919 



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PREFACE 

The great World War was more than two- 
thirds over when America entered the struggle, 
and yet in a sense this country was in the war 
from its very beginning. Three great inven- 
tions controlled the character of the fighting 
and made it different from any other the world 
has ever seen. These three inventions were 
American. The submarine was our invention ; 
it carried the war into the «sea. The airplane 
was an American invention ; it carried the war 
into the sky. We invented the machine gun ; it 
drove the. war into the ground. 

It is not my purpose to boast of American 
genius but, rather, to show that we entered the 
war with heavy responsibilities. The inven- 
tions we had given to the world had been de- 
veloped marvelously in other lands. Further- 
more they were in the hands of a determined 
and unscrupulous foe, and we found before us 
the task of overcoming the very machines that 
we had created. Yankee ingenuity was faced 
with a real test. 



vi PREFACE 

The only way of overcoming the airplane was 
to build more and better machines than the en- 
emy possessed. This we tried to do, but first 
we had to be taught by our allies the latest re- 
finements of this machine, and the war was over 
before we had more than started our aerial pro- 
gram. The machine gun and its accessory, 
barbed wire (also an American invention), were 
overcome by the tank; and we may find what 
little comfort we can in the fact that its inven- 
tion was inspired by the sight of an American 
farm tractor. But the tank was a British cre- 
ation and was undoubtedly the most important 
invention of the war. On the sea we were faced 
with a most baffling problem. The U-boat could 
not be coped with by the building of swarms of 
submarines. The essential here was a means 
of locating the enemy and destroying him even 
while he lurked under the surface. Two Amer- 
ican inventions, the hydrophone and the depth 
bomb, made the lot of the U-boat decidedly un- 
enviable and they hastened if they did not ac- 
tually end German frightfulness on the sea. 

But these were by no means the only inven- 
tions of the war. Great Britain showed won- 
derful ingenuity and resourcefulness in many 



PREFACE vii 

directions; France did marvels with the air- 
plane and showed great cleverness in her devel- 
opment of the tank and there was a host of 
minor inventions to her credit; while Italy 
showed marked skill in the creation of large air- 
planes and small seacraft. 

The Central Powers, on the other hand, were 
less originative but showed marked resourceful- 
ness in developing the inventions of others. 
Forts were made valueless by the large portable 
Austrian guns. The long range gun that 
shelled Paris was a sensational achievement, 
but it cannot be called a great invention because 
it was of little military value. The great Ger- 
man Zeppelins were far from a success because 
they depended for their buoyancy on a highly 
inflammable gas. It is interesting to note that 
while the Germans were acknowledging the fail- 
ure of their dirigibles the British were launch- 
ing an airship program, and here in America 
we had found an economical way of producing a 
non-inflammable balloon gas which promises a 
great future for aerial navigation. 

The most important German contribution to 
the war — it cannot be classed as an invention — 
was poison gas, and it was not long ere they re- 



viii PREFACE 

gretted this infraction of the rules of civilized 
warfare adopted at the Hague Conference ; for 
the Allies soon gave them a big dose of their 
own medicine and before the war was over, 
fairly deluged them with lethal gases of every 
variety. 

Many inventions of our own and of our allies 
were not fully developed when the war ended, 
and there were some which, although primarily 
intended for purposes of war, will be most serv- 
iceable in time of peace. For this war was not 
one of mere destruction. It set men to thinking 
as they had never thought before. It intensi- 
fied their inventive faculties, and as a result, the 
world is richer in many ways. Lessons of 
thrift and economy have been taught us. Man- 
ufacturers have learned the value of standardi- 
zation, The business man has gained an appre- 
ciation of scientific research. 

The whole story is too big to be contained 
within the covers of a single book, but I have 
selected the more important and interesting in- 
ventions and have endeavored to describe them 
in simple language for the benefit of the reader 
who is not technically trained. 

A. Russell Bond 

New York, May, 1919 



CONTENTS 

CHAPTER PAGE 

I The War In and Under the Ground . 3 

II Hand- Grenades and Trench Mortars . 20 

III Guns that Fire Themselves .... 41 

IV Guns and Super-Guns 62 

V The Battle of the Chemists .... 85 

VI Tanks 107 

VII The War in the Air ..... . 123 

VIII Ships that Sail the Skies .... 148 

IX Getting the Range 169 

X Talking in the Sky 184 

XI Warriors op the Paint-Brush . . . 209 

XII Submarines 232 

XIII Getting the Best of the U-Boat . . 253 

XIV "Devil's Eggs" . 276 

XV Surface Boats 298 

XVI . Reclaiming the Victims of the Subma- 
rines 310 

Index 339 



LIST OF ILLUSTRATIONS 



Oil-tempering the lining of a big gun . Frontispiece 

FACING 
PAGE 

Lines of zig-zag trenches as viewed from an aero- 
plane 8 

French sappers using stethoscopes to detect the 

mining operations of the enemy .... 9 

A 3-inch Stokes mortar and two of its shells . . 86 

Dropping a shell into a 6-inch trench mortar . 36 
The Maxim machine-gun operated by the energy 

of the recoil 37 

Colt machine-gun partly broken away to show the 

operating mechanism 37 

The Lewis gun which produces its own cooling 

current 44 

The Benet-Mercie gun operated by gas . . . 44 . 

Browning machine gun, weighing 34% pounds . 45 

Browning machine rifle, weight only 15 pounds 45 

Lewis machine-guns in action at the front . . 52 

An elaborate German machine-gun fort ... 53 
Comparative diagram of the path of a projectile 

from the German super-gun 60 

One of our 16-inch coast defence guns on a dis- 
appearing mount 61 

Height of gun as compared with the New York 

City Hall 61 

The 121-mile gun designed by American ordnance 

officer . ■ 68 

American 16-inch rifle on a railway mount . . 69 

xi 



xii ILLUSTRATIONS 



FACING 
PAGE 



A long-distance sub-ealibered French gun on a 

railway mount 76 

Inside of a shrapnel shell and details of the fuse 

cap 77 

Searchlight shell and one of its candles . . . 77 
Putting on the gas masks to meet a gas cloud at- 
tack ..... 84 i 

Even the horses had to be masked 85 

Portable flame-throwing apparatus .... 85 
Liquid fire streaming from fixed flame-throwing 

apparatus 92 

Cleaning up a dugout with the "fire-broom" . 93 
British tank climbing out of a trench at Cambrai 112 
Even trees were no barrier to the British tank . 113 
The German tank was very heavy and cumber- 
some ..... 113 

The speedy British "Whippet" tank that can 

travel at a speed of twelve miles per hour . 120 
The French high-speed "baby" tank . . . .120 
Section through our Mark VIII tank showing the 

layout of the interior 121 

A Handley-Page bombing plane with one of its 

wings folded back 128 

How an object dropped from the Woolworth 

Building would increase its speed in falling 129 
Machine gun mounted to fire over the blades of 

the propeller 136 

Mechanism for firing between the blades of the 

propeller 136 

It would take a hundred horses to supply the 

power for a small airplane ...... 137 

The flying-tank 144 

An N-C (Navy-Curtiss) seaplane of the type that 

made the first flight across the Atlantic . . 145 
A big German Zeppelin that was forced to come 

down on French soil 148 



ILLUSTRATIONS xiii 

FACING 
PAGE 

Observation car lowered from a Zeppelin sailing 

above the clouds 149 

Giant British dirigible built along the lines of a 
Zeppelin 156 

One of the engine cars or * ' power eggs ' ' of a Brit- 
ish dirigible 156 

Crew of the C-5 (American coastal dirigible) 
starting for Newfoundland to make a trans- 
atlantic flight (. 157 

The curious tail of a kite balloon 160 

Observers in the basket of an observation balloon 160 

Enormous range-finders mounted on a gun turret 

of an American warship 161 

British anti-aircraft section getting the range of 

an enemy aviator 176 

A British aviator making observations over the 

German lines 177 

Radio headgear of an airman 192 

Carrying on conversation by radio with an aviator 

miles away 192 

Long distance radio apparatus at the Arlington 

(Va.) station 193 

A giant gun concealed among trees behind the 

French lines 212 

Observing the enemy from a papier-mache replica 

of a dead horse 213 

Camouflaged headquarters of the American 26th 

Division in France 220 

A camouflaged ship in the Hudson River on Vic- 
tory Day 221 

Complex mass of wheels and dials inside a German 

submarine 240 ' 

Surrendered German submarines, showing the net 

cutters at the bow 241 

Forward end of a U-boat ,..,,.. 256 



X1T 



ILLUSTRATIONS 



TAcnsra 

PAGE 



A depth-bomb mortar and a set of "ash cans" at 

the stern of an American destroyer . . .257 

A depth bomb mortar in action and a depth bomb 
snapped as it is being hurled through the 
air 260 

Airplane stunning a U-boat with a depth bomb . 261 

The false hatch of a mystery ship 268 

The same hatch opened to disclose the 3-inch gun 

and crew 268 

A French hydrophone installation with which the 

presence of submarines was detected . .269 

Section of a captured mine-laying U-boat . . 272 

A paravane hauled up with a shark caught in its 

jaws ,. ... 273 

A Dutch mine-sweeper engaged in clearing the 

North Sea of German mines 288 

Hooking up enemy anchored mines .... 289 

An Italian "sea tank" climbing over a harbor 

boom 300 

Deck of a British aircraft mothership or "hush 
ship" ' . . 301 

Electrically propelled boat or surface torpedo, at- 
tacking a warship 304 

Hauling a seaplane up on a barge so that it may 

be towed 305 

Climbing into an armored diving suit . . . .320 

Lowering an armored diver into the water . . 320 

A diver's sea sled ready to be towed along the 

bed of the sea 321 

The sea sled on land showing the forward horizon- 
tal and after vertical rudders 321 

The diving sphere built for deep sea salvage op- 
erations ............ 324 

The pneumatic breakwater 325 



INVENTIONS 
OF THE GREAT WAR 



INVENTIONS 
OF THE GREAT WAR 

CHAPTEE I 
The War in and Under the Ground 

FOR years the Germans had been preparing 
for war. The whole world knew this, 
but it had no idea how elaborate were their 
preparations, and how these were carried ont 
to the very minutest detail. When the call to 
arms was sounded, it was a matter of only a 
few hours before a vast army had been assem- 
bled — fully armed, completely equipped, ready 
to swarm over the frontiers into Belgium and 
thence into France. It took much longer for 
the French to raise their armies of defense, 
and still longer for the British to furnish 
France with any adequate help. Despite the 
heroic resistance of Belgium, the Entente Allies 
were unprepared to stem the tide of German 

3 



4 INVENTIONS OF THE GREAT WAR 

soldiers who poured into the northern part of 
France. 

So easy did the march to Paris seem, that the 
Germans grew careless in their advance and 
then suddenly they met with a reverse that sent 
them back in full retreat. However, the mili- 
tary authorities of Germany had studied not 
only how to attack but also how to retreat and 
how to stand on the defensive. In this, as in 
every other phase of the conflict, they were far 
in advance of the rest of the world, and after 
their defeat in the First Battle of the Marne, 
they retired to a strong position and hastily 
prepared to stand on the defensive. When 
the Allies tried to drive them farther back, they 
found that the German army had simply sunk 
into the ground. The war of manoeuver had 
given way to trench warfare, which lasted 
through long, tedious months nearly to the end 
of the great conflict. 

The Germans found it necessary to make the 
stand because the Eussians were putting up 
such a strong fight on Germany's eastern fron- 
tier. Men had to be withdrawn from the west- 
ern front to stem the Russian tide, which meant 
that the western armies of the kaiser had to 



WAR IN AND UNDER THE GROUND 5 

cease their offensive activities for the time be- 
ing. The delay was fatal to the Germans, for 
they had opposed to *them not only brave men 
but intelligent men who were quick to learn. 
And when the Germans were ready to resume 
operations in the West, they found that the 
Allies also had sunk into the ground and had 
learned all their tricks of trench warfare, add- 
ing a number of new ones of their own. 

The whole character of the war was changed. 
The opposing forces were dead-locked and 
neither could break through the other's lines. 
The idea of digging into the ground did not 
originate with this war, but never before had 
it been carried out on so extensive a scale. 
The inventive faculties of both sides were vainly 
exercised to find some way of breaking the 
dead-lock. 'Hundreds of new inventions were 
developed. The history of war from the days 
of the ancient Eomans up to the present time 
was searched for some means of breaking down 
the opposing lines. However, the dead-lock 
was not broken until a special machine had been 
invented, a traveling fort. But the story of 
that machine is told in another chapter. 

At the outset the Allies dug very shallow 



6 INVENTIONS OF THE GREAT WAR 

ditches, such as had been used in previous 
wars. When it was found that these burrows 
would have to be occupied for weeks and months, 
the French and British imitated the Germans 
and dug their trenches so deep that men could 
walk through them freely, without danger of ex- 
posing their heads above ground; and as the 
ditches grew deeper, they had to be provided 
with a firing-step on which the riflemen could 
stand to fire over the top of the trenches. The 
trenches were zig-zagged so that they could not 
be flanked, otherwise they would have made dan- 
gerous traps for the defenders; for had the 
enemy gained one end of the trench, he could 
have fired down the full length of it, killing or 
wounding every man it contained. But zig- 
zagging made it necessary to capture each turn 
separately. There were lines upon lines of 
these trenches. Ordinarily there were but 
three lines, several hundred feet apart, with 
communicating trenches connecting them, and 
then several kilometers x farther back were re- 
serve trenches, also connected by communicat- 
ing trenches with the front lines. 

i A kilometer is, roughly, six tenths of a mile ; or six miles 
would equal ten kilometers. 



WAR IN AND UNDER THE GROUND 7 

Men did not dare to show themselves out in 
the open near the battle-front for a mile or more 
behind the front-line trenches, for the enemy's 
sharp-shooters were always on the watch for a 
target. The men had to stay in the trenches 
day and night for two or more weeks at a time, 
and sleeping-accommodations of a very rough 
sort were provided for them in dugouts which 
opened into the trenches. The dugouts of the 
Allies were comparatively crude affairs, but the 
Germans spent a great deal of time upon their 
burrows. 

UNDERGROUND VILLAGES 

When the French first swept the Germans 
back out of their trenches along the Aisne, they 
were astonished to find how elaborate were these 
underground dwellings. They found that the 
ground was literally honeycombed with rooms 
and passageways. Often the dugouts were 
two stories in depth and extended as much as 
sixty feet below the level of the ground. In 
fact, all along this part of the front, the Ger- 
mans had a continuous underground village in 
which thousands of men were maintained. The 
officers' quarters were particularly well fitted 



8 INVENTIONS OF THE GREAT WAR 

up, and every attention was given to the com- 
fort of their occupants. There were steel 
door-mats at the entrances of the quarters. 
The walls were boarded and even papered. 
The bedrooms were fitted with spring beds, 
chiffoniers, and wash-stands, and all the rooms 
were lighted with electric lamps. There were 
spacious quarters for the men, with regular 
underground mess halls and elaborate kitchens. 
There were power-plants to furnish steam for 
the operation of pumps and for the lighting- 
plants and for other purposes. 

There was a chalk formation here in wmich 
were many large natural caves. One enormous 
cave was said to have held thirty thousand 
soldiers, and in this section the Germans kept 
large reserve forces. By digging far into the 
ground, the German troops secured protection 
from shell-fire; in fact, the horrible noise of 
battle was heard only as a murmur, down in 
these depths. "With characteristic thorough- 
ness, the Germans built their trench system for 
a long stay; while the Allies, on the other hand, 
looked upon their trenches as merely temporary 
quarters, which would hold the enemy at bay 
until they could build up armies large enough 




(C) Underwood & Underwood 

Lines of Zig-Zag Trenches as viewed from an Airplane 




Courtesy of "Scientific American " 

French Sappers using Stethoscopes to detect the 
Mining Operations of the Enemy 



WAR IN AND UNDER THE GROUND 9 

to drive the invaders out of the country. The 
construction of the trenches along some parts 
of the battle-line was particularly difficult, be- 
cause of the problem of drainage. This was 
especially true in Flanders, where the trenches 
in many cases were below water-level, and 
elaborate pumping-systems had to be installed 
to keep them dry. Some of them were concrete- 
lined to make them waterproof. In the early 
stages of the war, before the trenches were 
drained, the men had to stand in water for a 
good part of the time, and the only way they 
could get about at all in the miry trenches was 
by having " duck-boards ' ' in them. Duck- 
boards are sections of wooden sidewalk such as 
we find in small villages in this country, con- 
sisting of a couple of rails on which crosspieces 
of wood are nailed. These duck-boards fairly 
floated in the mud. 

Some of the trenches were provided with 
barbed-wire barriers or gates calculated to halt 
a raiding-party if it succeeded in getting into 
the trench. These gates were swung up out 
of the way, but when lowered they were kept 
closed with a rather complicated system of bolts 
which the enemy would be unable to unfasten 



10 INVENTIONS OF THE GREAT WAR 

without some delay; and while he was strug- 
gling to get through the gate, he would be a 
target for the bullets of the defenders. 

HIDING RAILROADS IN DITCHES 

Because of the elaborate system of trenches, 
and the distance from the front line to that part 
of the country where it was safe to operate in 
the open, it was necessary to build railways 
which would travel through tunnels and com- 
municating trenches to the front lines. These 
were narrow-gage railroads and a special stan- 
dard form of track section was designed, which 
was entirely of metal, something like the track 
sections of toy railroads. The tracks were 
very quickly laid and taken up at need. The 
locomotives had to be silent and smokeless and 
so a special form of gasolene locomotive was 
invented to haul the little cars along these minia- 
ture railroads to the front lines. Usually the 
trench railroads did not come to the very front 
of the battle-line, but their principal use was 
to carry shell to the guns which were located 
in concealed positions. Eailroad or tramway 
trenches could not be sharply zig-zagged but had 
to. have easy curves, which were apt to be recog- 



WAR IN AND UNDER THE GROUND 11 

nized by enemy airplanes, and so they were 
often concealed under a covering of wire strewn 
with leaves. 

PEKISCOPES AND u SNIPERSCOPES , ' 

But while the armies were buried under- 
ground, it was necessary for them to keep their 
eyes upon each other so that each might be 
ready for any sudden onslaught of the other. 
Snipers were always ready to fire at any head 
that showed itself above the parapet of the 
trench and so the soldiers had to steal an idea 
from the submarines and build them periscopes 
with which they could look over the top of their 
trenches without exposing themselves. A 
trench periscope was a very simple affair, con- 
sisting of a tube with two mirrors, one at the 
top and one at the bottom, set at such an angle 
that a person looking into the side of the tube 
at the bottom could see out of the opposite side 
of the tube at the top. 

Observation posts were established wherever 
there was a slight rise in the ground. Some- 
times these posts were placed far in advance of 
the trenches and sometimes even behind the 
trenches where it was possible to obtain a good 



12 INVENTIONS OF THE GREAT WAR 

view of the opposing lines. Sometimes a tunnel 
would be dug forward, leading to an outlet 
close to the enemy's lines, and here an observer 
would take his position at night to spy with his 
ears upon the activities of the enemy. Ob- 
servers who watched the enemy by day would 
often not dare to use periscopes, which might 
be seen by the enemy and draw a concentrated 
fire of rifles and even shell. So that every 
manner of concealment was employed to make 
the observation posts invisible and to have 
them blend with their surroundings. Observ- 
ers even wore veils so that the white of their 
skin would not betray them. 

Snipers were equally ingenious in concealing 
themselves. They frequently used rifles which 
were connected with a dummy butt and had 
a periscope sighting-attachment. This attach- 
ment was called a "sniperscope." The rifle- 
barrel could be pushed through a loophole in 
the parapet and the sniper standing safely be- 
low the parapet could hold the dummy butt to 
his shoulder and aim his rifle with perfect ac- 
curacy by means of the periscope. It was next 
to impossible to locate a sniper hidden in this 
way. One method of doing it was to examine 



WAR IN AND UNDER THE GROUND 13 

rubbish, tin cans, or any object that had been 
penetrated by a bullet and note the direction 
taken by the bullet. This would give a line 
leading toward the source of the shot, and 
when a number of such lines were traced, they 




Redrawn from Military Map Reading by permission of E. C. McKay 
Fig. 1. A "sniperscope" with which a sharpshooter could take 
aim without showing his head above the parapet 

would cross at a spot where the sniper or 
his gun was stationed, and a few shell would 
put the man out of business. Dummy heads 
of papier mache were sometimes stuck above 
the parapet to draw the fire of enemy snip- 
ers and the bullet-holes which quickly ap- 



14 INVENTIONS OF THE GREAT WAR 

peared in them were studied to discover the lo- 
cation of the snipers. 

Sometimes fixed rifles were used. These 
were set on stands so that 'they could be very 
accurately trained upon some important enemy 




Redrawn from Military Map Reading by permission of E. C. McKay 
Fig. 2. A fixed rifle stand arranged to be fired after dark 

post. Then they could be fired in the dark, 
.without aiming, to disturb night operations of 
the enemy. Often a brace of rifles, as many as 
six, would be coupled up to be fired simultane- 
ously, and by operating a single lever each gun 
would throw out the empty cartridge shell and 
bring a fresh one into position. 



WAR IN AND UNDER THE GROUND 15 

STEEL BEIER PATCHES 

The most important defense of a trench sys- 
tem consisted in the barbed-wire entanglements 
placed before' it. Barbed wire, by the way, is 
an American invention, but it was originally 
intended for the very peaceful purpose for keep- 
ing cattle within bounds. Long ago it was used 
in war, but never to the extent to which it was 
employed in this world struggle. The entangle- 
ments were usually set up at night and were 
merely fences consisting of stout posts driven 
into the ground and strung with barbed wire 
running in all directions, so as to make an im- 
penetrable tangle. Where it was possible to 
prepare the entanglements without disturbance 
and the position was an important one, the mass 
of barbed wire often extended for a hundred 
yards or more in depth. Just beyond the en- 
tanglements trip-wires were sometimes used. 
A trip-wire was a slack wire which was laid on 
the ground. Before being laid, the wire was 
tightly coiled so that it would not lie flat, but 
would catch the feet of raiders and trip them up. 
Each side had "gates" in the line through 
which this wire could quickly be removed to 



16 INVENTIONS OF THE GREAT WAR 

let its own raiding-parties through. Some- 
times raiders used tunnels, with outlets be- 
yond the barbed wire, but they had to cut their 
way through the metal brier patches of their 
opponents. 

Early in the war, various schemes were de- 
vised for destroying the entanglements. There 
were bombs in the form of a rod about twelve 
feet long, which could be pushed under the wire 
and upon exploding would tear it apart. An- 
other scheme was to fire a projectile formed 
like a grapnel. The projectile was attached 
to the end of a cable and was fired from a 
small gun in the same way that life-lines are 
thrown out to wrecks near shore. Then the 
cable would be wound up on a winch and the 
grapnel hooks would tear the wire from its fast- 
enings. Such schemes, however, did not prove 
very practicable, and it was eventually found 
that a much better way of destroying barbed 
wire was to bombard it with high-explosive 
shell, which would literally blow the wire apart. 
But it required a great deal of shelling to de- 
stroy these entanglements, and it was really 
not until the tank was invented that such ob- 
structions could be flattened out so that they 



WAR IN AND UNDER THE GROUND 17 

formed no bar to the passage of the soldiers. 
The Germans not only used fixed entangle- 
ments, but they had large standard sections 
of barbed wire arranged in the form of big 
cylindrical frames which would be carried 
easily by a couple of men and could be placed 
in position at a moment's notice to close a gap 
in the line or even to build up new lines of wire 
obstruction. 

MINES AND COUNTER-MINES 

In the earlier stages of the war it proved so 
impossible to capture a trench when it was well 
defended by machine-guns that efforts were 
made to blow up the enemy by means of mines. 
Tunnels were dug reaching out under the 
enemy's lines and large quantities of explo- 
sives were stored in them. At the moment when 
it was intended to make an assault, there would 
be a heavy cannonading to disconcert the enemy, 
and then the mine would be touched off. In 
the demoralizing confusion that resulted, the 
storming-party would sweep over the enemy. 
Such mines were tried on both sides, and the 
only protection against them was to out-guess 
the other side and build counter-mines. 



18 INVENTIONS OF THE GREAT WAR 

If it were suspected, from the importance of 
a certain position and the nature of the ground, 
that the enemy would probably try to under- 
mine it, the defenders would dig tunnels of their 
own toward the enemy at a safe distance be- 
yond their own lines and establish listeners 
there to see if they could hear the mining- 
operations of their opponents. Very delicate 
microphones were used, which the listeners 
would place on the ground or against the walls 
of their tunnel. Then they would listen for the 
faintest sound of digging, just as a doctor 
listens through a stethoscope to the beating 
of a patient's heart or the rush of air through 
his lungs. When these listening-instruments 
picked up the noise of digging, the general di- 
rection of the digging could be followed out by 
placing the instrument at different positions 
and noting where the noise was loudest. Then 
a counter-mine would be extended in that direc- 
tion, far enough down to pass under the enemy's 
tunnel, and at the right moment, a charge of 
TNT (trinitrotoluol) would be exploded, which 
would destroy the enemy's sappers and put an 
end to their ambitious plans. 

A very interesting case of mining was fur- 



WAR IN AND UNDER THE GROUND 19 

nished by the British when they blew up the im- 
portant post of Messines Ridge. This was 
strongly held by the Germans and the only way 
of dislodging the enemy was to blow off the top 
of the ridge. Before work was started, geolo- 
gists were called upon to determine whether 
or not the ground were suitable for mining- 
operations. They picked out a spot where the 
digging was good from the British side, but 
where, if counter-mines were attempted from 
the German side, quicksands would be encount- 
ered and tunneling of any sort would be diffi- 
cult. The British sappers could, therefore, pro- 
ceed with comparative safety. The Germans 
suspected that something of the sort was being 
undertaken, but they found it very difficult to 
dig counter-mines. However, one day their 
suspicions were confirmed, when the whole top 
of the hill was blown off, with a big loss of 
German lives. In the assault that followed the 
British captured the position and it was an- 
nexed to the British lines. 



CHAPTER II 

Hand-Grenades and Trench Mortars 

IN primitive times battles were fought hand- 
to-hand. The first implements of war were 
clubs and spears and battle-axes, all intended 
for fighting at close quarters. The bow and ar- 
row enabled men to fight at a distance, but 
shields and armor were so effective a defense 
that it was only by hand-to-hand fighting that a 
brave enemy could be defeated. Even the in- 
vention of gunpowder did not separate the com- 
batants permanently, for although it was possi- 
ble to hurl missiles at a great distance, cannon 
were so slow in their action that the enemy could 
rush them between shots. Shoulder firearms 
also were comparatively slow in the early days, 
and liable to miss fire, and it was not until the 
automatic rifle of recent years was fully de- 
veloped that soldiers learned to keep their dis- 
tance. 

When the great European war started, mili- 
tary authorities had come to look upon war at 

20 



HAND-GRENADES 21 

close quarters as something relegated to by- 
gone days. Even the bayonet was beginning 
to be thought of little use. Rifles could be 
charged and fired so rapidly and machine-guns 
could play such a rapid tattoo of bullets, that 
it seemed impossible for men to come near 
enough for hand-to-hand fighting, except at a 
fearful cost of life. In developing the rifle, 
every effort was made to increase its range so 
that it could be used with accuracy at a distance 
of a thousand yards and more. But when the 
Germans, after their retreat in the First Battle 
of the Marne, dug themselves in behind the 
Aisne, and the French and British too found it 
necessary to seek shelter from machine-gun and 
rifle fire by burrowing into the ground, it be- 
came apparent that while rifles and machine- 
guns could drive the fighting into the ground, 
they were of little value in continuing the fight 
after the opposing sides had buried themselves. 
The trenches were carried close to one another, 
in some instances being so close that the 
soldiers could actually hear the conversation of 
their opponents across the intervening gap. Un- 
der such conditions long-distance firearms were 
of very little practical value. What was needed 



22 INVENTIONS OF THE GREAT WAR 

was a short-distance gun which would get down 
into the enemy trenches. To be sure, the 
trenches could be shelled, but the shelling had to 
be conducted from a considerable distance, 
where the artillery would be immune to attack, 
and it was impossible to give a trench the par- 
ticular and individual attention which it would 
receive at the hands of men attacking it at 
close quarters. 

Before we go any farther we must learn the 
meaning of the word " trajectory. " No bullet 
or shell travels in a straight line. As soon as 
it leaves the muzzle of the gun, it begins to fall, 
and its course through the air is a vertical 
curve that brings it eventually down to the 
ground. This curve is called the " trajectory." 
No gun is pointed directly at a target, but above 
it, so as to allow for the pull of gravity. The 
faster the bullet travels, the flatter is this curve 
or trajectory, because there is less time for it 
to fall before it reaches its target. Modern 
rifles fire their missiles at so high a speed that 
the bullets have a very flat trajectory. But in 
trench warfare a flat trajectory was not de- 
sired. What was the use of a missile that trav- 
eled in a nearly straight line, when the object to 



HAND-GRENADES 23 

be hit was hiding in the ground? Trench fight- 
ing called for a missile that had a very high tra- 
jectory, so that it would drop right into the 
enemy trench. 

HAND-AETILLEEY 

Trench warfare is really a close-quarters 
fight of fort against fort, and the soldiers who 
manned the forts had to revert to the ancient 
methods of fighting an enemy intrenched be- 
hind fortifications. Centuries ago, not long 
after the first use of gunpowder in war, small 
explosive missiles were invented which could be 
thrown by hand. These were originally known 
as "flying mortars." The missile was about 
the size of an orange or a pomegranate, and it 
was filled with powder and slugs. A small fuse, 
which was ignited just before the device was 
thrown, was timed to explode the missile when 
it reached the enemy. Because of its size and 
shape, and because the slugs it contained corre- 
sponded, in a manner, to the pulp-covered seeds 
with which a pomegranate is filled, the missile 
was called a "grenade." 

Grenades had fallen out of use in modern war- 
fare, although they had been revived to a small 



24 INVENTIONS OF THE GREAT WAR 

extent in the Eusso-Japanese war, and had been 
used with some success by the Bulgarians and 
the Turks in the Balkan wars. And yet they 
had not been taken very seriously by the mili- 
tary powers of Europe, except Germany. Ger- 
many was always on the lookout for any device 
that might prove useful in war, and when the 
Germans dug themselves in after the First Bat- 
tle of the Marne, they had large quantities of 
hand-grenades for their men to toss over into 
the trenches of the Allies. These missiles 
proved very destructive indeed. They took the 
place of artillery, and were virtually hand- 
thrown shrapnel. 

The French and British were entirely unpre- 
pared for this kind of fighting, and they had 
hastily to improvise offensive and defensive 
weapons for trench warfare. Their hand- 
grenades were at first merely tin cans filled 
with bits of iron and a high explosive in which 
a fuse-cord was inserted. The cord was lighted 
by means of a cigarette and then the can with 
its spluttering fuse was thrown into the enemy 
lines. As time went on and the art of grenade 
fighting was learned, the first crude missiles 
were greatly improved upon and grenades were 



HAND-GRENADES 25 

made in many forms for special service. 

There was a difference between grenades 
hurled from sheltered positions and those used 
in open fighting. When the throwers were 
sheltered behind their own breastworks, it mat- 
tered not how powerful was the explosion of the 
grenade. We must remember that in "hand- 
artillery" the shell is far more powerful in pro- 
portion to the distance it is thrown than the 
shell fired from a gun, and many grenades were 
so heavily charged with explosives that they 
would scatter death and destruction farther 
than they could be thrown by hand. The grena- 
dier who cast one of these grenades had to 
duck under cover or hide under the walls of 
his trench, else the fragments scattered by the 
exploding missile might fly back and injure him. 
Some grenades would spread destruction to a 
distance of over three hundred feet from the 
point of explosion. For close work, grenades 
of smaller radius were used. These were em- 
ployed to fight off a raiding-party after it had 
invaded a trench, and the destructive range of 
these grenades was usually about twenty-five 
feet. 

Hand-grenades came to be used in all the 



26 INVENTIONS OF THE GREAT WAR 

different ways that artillery was used. There 
were grenades which were filled with gas, not 
only of the suffocating and tear-producing 
types, but also of the deadly poisonous variety. 
There were incendiary grenades which would 
set fire to enemy stores, and smoke grenades 
which would produce a dense black screen be- 
hind which operations could be concealed from 
the enemy. Grenades were used in the same 
way that shrapnel was used to produce a bar- 
rage or curtain of fire, through which the enemy 
could not pass without facing almost certain 
death. Curtains of fire were used not only for 
defensive purposes when the enemy was attack- 
ing, but also to cut off a part of the enemy so 
that it could not receive assistance and would 
be obliged to surrender. In attacks upon the 
enemy lines, grenades were used to throw a 
barrage in advance of the attacking soldiers so 
as to sweep the ground ahead clear of the 
enemy. 

The French paid particular attention to the 
training of grenadiers. A man had to be a 
good, cool-headed pitcher before he could be 
classed as a grenadier. He must be able to 
throw his grenade with perfect accuracy up to 



HAND-GRENADES 27 

a distance of seventy yards, and to maintain an 
effective barrage. The grenadier carried his 
grenades in large pockets attached to his belt, 
and he was attended by a carrier who brought 
up grenades to him in baskets, so that he was 
served with a continuous supply. 

LONG-DISTANCE GEENADE-THEOWING 

All this relates to short-distance fighting, but 
grenades were also used for ranges beyond the 
reach of the pitcher's arm. Even back in the 
sixteenth century, the range of the human arm 
was not great enough to satisfy the combatants 
and grenadiers used a throwing-implement, 
something like a shovel, with which the grenade 
was slung to a greater distance, in much the 
same way as a lacrosse ball is thrown. Later, 
grenades were fitted with light, flexible wooden 
handles and were thrown, handle and all, at the 
enemy. By this means they could be slung to 
a considerable distance. Such grenades were 
used in the recent war, particularly by the Ger- 
mans. The handle was provided with streamers 
so as to keep the grenade head-on to the enemy, 
and it was usually exploded by percussion on 
striking its target. These long-handled gre- 



28 INVENTIONS OF THE GREAT WAR 



A 



(flf 



Fig. 3. 



A rifle grenade 
fitted to the 
muzzle of a rifle 



nades, however, were clumsy 
and bulky, and the grenadier re- 
quired a good deal of elbow- 
room when throwing them. 

A much better plan was to 
hurl them with the aid of a gun. 
A rifle made an excellent short- 
distance mortar. With it gre- 
nades could be thrown from 
three to four hundred yards. 
The grenade was fastened on a 
rod which was inserted in the 
barrel of the rifle and then it was 
fired out of the gun by the ex- 
plosion of a blank cartridge. 
The butt of the rifle was rested 
on the ground and the rifle was 
tilted so as to throw the grenade 
up into the air in the way that 
a mortar projects its shell. 

STRIKING A LIGHT 

The lighting of the grenade 
fuses with a cigarette did very 
well for the early tin-can gre- 
nades, but the cigarettes were 



HAND-GRENADES 29 

not always handy, particularly in the heat 
of battle, and something better had to be de- 
vised. One scheme was to use a safety- 
match composition on the end of a fuse. This 
was covered with waxed paper to protect 
it from the weather. The grenadier wore 
an armlet covered with a friction compo- 
sition such as is used on a safety-match box. 
Before the grenade was thrown, the waxed 
paper was stripped off and the fuse was lighted 
by being scratched on the armlet. In another 
type the fuse was lighted by the twisting of a 
cap which scratched a match composition on a 
friction surface. A safety-pin kept the cap 
from turning until the grenadier was ready to 
throw the grenade. 

The Mills hand-grenade, which proved to be 
the most popular type used by the British Army, 
was provided with a lever which was normally 
strapped down and held by means of a safety- 
pin. Fig. 4 shows a sectional view of this 
grenade. Just before the missile was thrown, 
it was seized in the hand so that the lever was 
held down. Then the safety-pin was removed 
and when the grenade was thrown, the lever 
would spring up under pull of the spring A. 



30 INVENTIONS OF THE GREAT WAR 

This would cause the pin B to strike the per- 
cussion cap C, which would light the fuse D. 
The burning fuse would eventually carry the fire 
to the detonator E, which would touch off the 
main explosive, shattering the shell of the gre- 
nade and scattering its fragments in all direc- 




Fig. 4. Details of the Mills hand grenade 



tions. The shell of the grenade was indented 
so that it would break easily into a great many 
small pieces. 

There were some advantages in using gre- 
nades lighted by fuse instead of percussion, 
and also there were many disadvantages. If 
too long a time-fuse were used, the enemy might 



HAND-GRENADES 



31 



catch the grenade, as you would a baseball and 
hurl it back before it exploded. This was a 
hazardous game, but it was often done. 

Among the different 
types of grenades which 
the Germans used was 
one provided with a par- 
achute as shown in Fig. 
5. The object of the par- 
achute was to keep the 
head of the grenade to- 
ward the enemy, so that 
when it exploded it would 
expend its energies for- 
ward and would not cast 
fragments back toward 
the man who had thrown 
it. This was a very sen- 
sitive grenade, arranged 
to be fired by percussion, 
but it was so easily ex- 
ploded that the firing- 
mechanism was not re- 
leased until after the 
grenade had been thrown. ^ 

Fig. 5. A German para 

In the handle of this gre- chute grenade 




32 INVENTIONS OF THE GREAT WAR 

nade there was a bit of cord about twenty feet 
long. One end of this was attached to a safety- 
needle, A, while the other end, formed into a 
loop, was held by the grenadier when he threw 
the grenade. Not" until the missile had reached 
a height of twelve or thirteen feet would the 
pull of the string withdraw the needle A. This 
would permit a safety-hook, B, to drop out of 
a ring, C, on the end of a striker pellet, D. 
When the grenade struck, the pellet D would 
move forward and a pin, E, would strike a cap 
on the detonator F, exploding the missile. This 
form of safety-device was used on a number of 
German grenades. 

The British had another scheme for locking 
the mechanism until after the grenade had 
traveled some distance through the air. De- 
tails of this grenade, which was of the type 
adopted to be fired from a rifle, are shown in 
Fig. 6. The striker A is retained by a couple 
of bolts, B, which in turn are held in place by 
a sleeve, C. On the sleeve is a set of wind- 
vanes, D. As the grenade travels through the 
air, the wind-vanes cause the sleeve C to re- 
volve, screwing it down clear of the bolts B, 
which then drop out, permitting the pin A to 




toliHililHWll 




U 



?. 1 1 % \ * * * j 

" 'l ' "., ill "■ " rt * 




Fig. 6. British rifle grenade with a safety-device which is 
unlocked by the rush of air against a set of inclined vanes, 
D, when the missile is in flight 



33 



34 INVENTIONS OF THE GREAT WAR 

strike the detonator E upon impact of the gre- 
nade with its target. 
The Germans had one peculiar type which 





Fig. 7. Front, side, and sectional views of a disk-shaped 
German grenade 

was in the shape of a disk. In the disk were 
six tubes, four of which carried percussion caps 
so that the grenade was sure to explode no mat- 
ter on which tube it fell. The disk was thrown 



Fig. 8. A curious German hand grenade shaped like a hair 
brush 

with the edge up, and it would roll through the 
air. Another type of grenade was known as 
the hair-brush grenade because it had a rectan- 



HAND-GRENADES 35 

gular body of tin about six inches long and two 
and three quarter inches wide and deep, which 
was nailed to a wooden handle. 

MINIATUKE ARTILLEEY 

Hand-artillery was very effective as far as 
it went, but it had its limitations. Grenades 
could not be made heavier than two pounds in 
weight if they were to be thrown by hand; in 
fact, most of them were much lighter than that. 
If they were fired from a rifle, the range was 
increased but the missile could not be made very 
much heavier. TNT is a very powerful ex- 
plosive, but there is not room for much of it 
in a grenade the size of a large lemon. Trench 
fighting was a duel between forts, and while the 
hand-artillery provided a means of attacking 
the defenders of a fort, it made no impression on 
the walls of the fort. It corresponded to shrap- 
nel fire on a miniature scale, and something 
corresponding to high-explosive fire on a small 
scale was necessary if the opposing fortifica- 
tions were to be destroyed. To meet this prob- 
lem, men cast their thoughts back to the primi- 
tive artillery of the Komans, who used to hurl 
great rocks at the enemy with catapults. And 



36 INVENTIONS OF THE GREAT WAR 

the trench fighters actually rigged up catapults 
with which they hurled heavy bombs at the 
enemy lines. All sorts of ingenious catapults 
were built, some modeled after the old Eoman 
machines. In some of these stout timbers were 
used as springs, in others there were powerful 
coil springs. It was not necessary to cast the 
bombs far. For distant work the regular ar- 
tillery could be used. What was needed was a 
short-distance gun for heavy missiles and that 
is what the catapult was. 

But the work of the catapult was not really 
satisfactory. The machine was clumsy ; it occu- 
pied too much space, and it could not be aimed 
very accurately. It soon gave way to a more 
modern apparatus, fashioned after the old 
smooth-bore mortars. This was a miniature 
mortar, short and wide-mouthed. A rifled bar- 
rel was not required, because, since the missile 
was not to be hurled far, it was not necessary to 
set it spinning by means of rifling so as to hold 
it head-on to the wind. 

GIANT PEA-SHOOTEES 

Better aim was secured when a longer-bar- 
reled trench mortar came to be used. In the 



HAND-GRENADES 37 

trench, weight was an important item. There 
was no room in which to handle heavy guns, and 
the mortar had to be portable so that it conld 
be carried forward by the infantry in a charge. 
As the walls of a light barrel might be burst 
by the shock of exploding powder, compressed 
air was used instead. The shell was virtually 
blown out of the gun in the same way that a boy 
blows missiles out of a pea-shooter. That the 
shell might be kept from tumbling, it was fitted 
with vanes at the rear. These acted like the 
feathers of an arrow to hold the missile head-on 
to its course. 

The French in particular used this type of 
mortar and the air-pump was used to compress 
the air that propelled the shell or aerial torpedo, 
or else the propelling charge was taken from 
a compressed-air tank. Carbon-dioxide, the 
gas used in soda water, is commonly stored in 
tanks under high pressure and this gas was 
sometimes used in place of compressed air. 
When the gas in the tank was exhausted the lat- 
ter could be recharged with air by using a hand- 
pump. Two or three hundred strokes of the 
pump would give a pressure of one hundred and 
twenty to one hundred and fifty pounds per inch, 



\ 



38 INVENTIONS OF THE GREAT WAR 

and would supply enough air to discharge a 
number of shell. The air was let into the bar- 
rel of the mortar in a single puff sufficient to 
launch the shell; then the tank was cut off at 
once, so that the air it contained would not 
escape and go to waste. 

THE STOKES MORTAB 

However, the most useful trench mortar de- 
veloped during the war was invented by Wilfred 
Stokes, a British inventor. In this a compara- 
tively slow-acting powder was used to propel 
the missile, and so a thin-walled barrel could 
be used. The light Stokes mortar can easily 
be carried over the shoulder by one man. It 
has two legs and the barrel itself serves as 
a third leg, and the mortar stands like a tripod. 
The two legs are adjustable, so that the barrel 
can be inclined to any desired angle. It took 
but a moment to set up the mortar for action in 
a trench or shell-hole. 

Curiously enough, there is no breech-block, 
trigger or fire-hole in this mortar. It is fired 
merely by the dropping of the missile into the 
mouth of the barrel. The shell carries its own 
propelling charge, as shown in Fig. 9. This 



HAND-GEENADES 



39 



is in the form of rings, A, which are fitted on 
a stem, B. At the end of the stem are a de- 
tonating cap and a cartridge, to ignite the 
propellant, A. At the bottom of the mortar 
barrel, there is a steel point, E, known as the 




Fig. 9. Sectional view of a 3-inch Stokes mortar showing a 
shell at the instant of striking the anvil 



"anvil." When the shell is dropped into the 
mortar, the cap strikes the anvil, exploding the 
cartridge and touching off the propelling 
charge, A. The gases formed by the burning 
charge hurl the shell out of the barrel to a 
distance of several hundred yards. 



40 INVENTIONS OF THE GREAT WAR 



/etyrftrf-yri 



The first Stokes mortar was made to fire a 
3-inch shell, but the mortar grew in size until 

it could hurl shell of 6- 
inch and even 8%-mch 
size. Of course, the 
larger mortars had to 
have a very substantial 
base. They were not so 
readily portable as the 
smaller ones and they 
could not be carried by 
one man; but compared 
with ordinary artillery of 
the same bore they were 
immeasurably lighter 
and could be brought to 
advanced positions and 
set up in a very short 
fig. 10. a 6-inch trench time. The larger shell 

mortar shell fitted with . 

taii-vanes have tail-vanes, as shown 

in Fig. 10, to keep them 
from tumbling when in flight. 




ft*/'— Cerr*;« s 



CHAPTEK in 

Guns that Fire Themselves 

MANY years ago a boy tried his hand at 
firing a United States Army service 
rifle. It was a heavy rifle of the Civil War 
period, and the lad did not know just how to 
hold it. He let the butt of the gun rest -un- 
certainly against him, instead of pressing it 
firmly to his shoulder, and, in consequence, when 
the gun went off he received a powerful kick. 

That kick made a deep impression on the 
lad, not only on his flesh but on his mind as 
well. It gave him a good conception of the 
power of a rifle cartridge. 

Years afterward, when he had moved to Eng- 
land, the memory of that kick was still with 
him. It was a useless prank of the gun, he 
thought, a waste of good energy. Why could 
not the energy be put to use 1 And so he set 
himself the task of harnessing the kick of the 
gun. 

41 



42 INVENTIONS OF THE GREAT WAR 

A very busy program lie worked out for that 
kick to perform. He planned to have the gun 
use up its exuberant energy in loading and fir- 
ing itself. So he arranged the cartridges on a 
belt and fed the belt into the gun. When the 
gun was fired, the recoil would unlock the breech, 
take out the empty case of the cartridge just 
fired, select a fresh cartridge from the belt, and 
cock the main spring ; then the mechanism would 
return, throwing the empty cartridge-case out 
of the gun, pushing the new cartridge into the 
barrel, closing the breech, and finally pulling 
the trigger. All this was to be done by the 
energy of a single kick, in about one tenth of a 
second, and the gun would keep on repeating the 
operation as long as the supply of cartridges 
was fed to it. The new gun proved so successful 
that the inventor was knighted, and became Sir 
Hiram Maxim. 

a doctor's ten-barreled gun 

But Maxim's was by no means the first ma- 
chine-gun. During the Civil War a Chicago 
physician brought out a very ingenious ten- 
barreled gun, the barrels of which were fired 
one after the other by the turning of a hand- 



GUNS THAT FIRE THEMSELVES 43 

crank. Although Dr. Gatling was a graduate 
of a medical school, he was far more fond of 
tinkering with machinery than of doling out 
pills. He invented a number of clever mechan- 
isms, but the -one that made him really famous 
was that machine-gun. At first our government 
did not take the invention seriously. The gun 
was tried out in the war, but whenever it went 
into battle it was fired not by soldiers but by a 
representative of Dr. Gatling 's company, who 
went into the army to demonstrate the worth of 
the invention. Not until long after was the 
Gatling gun officially adopted by our army. 
Then it was taken up by many of the European 
armies as well. 

Although many other machine-guns were in- 
vented, the Gatling was easily the best and most 
serviceable, until the Maxim invention made its 
appearance, and even then it held its own for 
many years ; but eventually it had to succumb. 
The Maxim did not have to be cranked: it 
fired itself, which was a distinct advantage; 
and then, instead of being a bundle of guns 
all bound up into a single machine, Maxim's 
was a single-barreled gun and hence was much 
lighter and could be handled much more easily. 



44 INVENTIONS OF THE GREAT WAR 

A GUN AS A GAS-ENGINE 

Another big advance was made by a third 
American, Mr. John M. Browning, who is re- 
sponsible for the Colt gun. It was not a kick 
that set Browning to thinking. He looked upon 
a gun as an engine of the same order as an 
automobile engine, and really the resemblance 
is very close. The barrel of the gun is the 
cylinder of the engine ; the bullet is the piston ; 
and for fuel gunpowder is used in place of gaso- 
lene. As in the automobile engine, the charge 
is fired by a spark; but in the case of the gun 
the spark is produced by a blow of the trigger 
upon a bit of fulminate of mercury in the end of 
the cartridge. 

Explosion is the same thing as burning. The 
only way that the explosion of gunpowder dif- 
fers from the burning of a stick of wood is that 
the latter is very slow, while the former goes 
like a flash. In both cases the fuel turns into 
great volumes of gas. In the case of the gun 
the gas is formed almost instantly and in such 
quantity that it has to drive the bullet out of 
the barrel to make room for itself. In the cart- 
ridge that our army uses, only about a tenth 



GUNS THAT FIRE THEMSELVES 45 

of an ounce of smokeless powder is used, but 
this builds up so heavy a pressure of gas that 
the bullet is sent speeding out of the gun at a 
rate of half a mile a second. It travels so fast 
that it will plow through four feet of solid wood 
before coming to a stop. 

Now it occurred to Browning that it wouldn't 
really be stealing to take a little of that gas- 
power and use it to work the mechanism of his 
machine-gun. It was ever so little he wanted, 
and the bullet would never miss it. The 
danger was not that he might take too much. 
His problem was to take any power at all with- 
out getting more than his mechanism could 
stand. What he did was to bore a hole through 
the side of the gun-barrel. When the gun was 
fired, nothing happened until the bullet passed 
this hole; then some of the gas that was push- 
ing the bullet before it would blow out through 
the hole. But this would be a very small 
amount indeed, for the instant that the bullet 
passed out of the barrel the gases would rush 
out after it, the pressure in the gun would drop, 
and the gas would stop blowing through the 
hole. With the bullet traveling at the rate of 
about half a mile in a second, imagine how short 



46 INVENTIONS OF THE GREAT WAR 

a space of time elapses after it passes the hole 
before it emerges from the muzzle, and what a 
small amount of gas can pass through the hole 
in that brief interval! 

The gas that Browning got in this way he 
led into a second cylinder, fitted with a piston. 
This piston was given a shove, and that gave 
a lever a kick which set going the mechanism 
that extracted the empty cartridge-case, in- 
serted a fresh cartridge, and fired it. 

GETTING RID OF HEAT 

The resemblance of a machine-gun to a gaso- 
lene-engine can be demonstrated still further. 
One of the most important parts of an auto- 
mobile engine is the cooling-system. The gaso- 
lene burning in the cylinders would soon make 
them red-hot, were not some means provided 
to carry ofT the heat. The same is true of a 
machine-gun. In fact, the heat is one of the 
biggest problems that has to be dealt with. In 
a gasolene-engine the heat is carried off in one 
of three ways: (1) by passing water around 
the cylinders; (2) by building flanges around 
the cylinders to carry the heat off into the air; 
and (3) by using a fan to blow cool air against 



GUNS THAT FIBE THEMSELVES 47 

the cylinders. All of these schemes are used 
in the machine-gun. In Dr. Gatling's gun the 
cooling-problem was very simple. As there 
were ten barrels, one barrel could be cooling 
while the rest were taking their turn in the 
firing. In other words, each barrel received 
only a tenth of the heat that the whole gun was 
producing; and yet Gatling found it advisable 
to surround the barrels for about half their 
length with a water-jacket. 

In the Maxim gun a water-jacket is used that 
extends the full length of the barrel, and into 
this waiter-jacket seven and a half pints of water 
are poured. Yet in a minute and a half of 
steady firing at a moderate rate, or before six 
hundred rounds are discharged, the water will 
be boiling. After that, with every thousand 
rounds of continuous fire a pint and a half of 
water will be evaporated. Now the water and 
the water-jacket add a great deal of weight to 
the gun, and this Browning decided to do away 
with in his machine-gun. Instead of water he 
used air to carry off the heat. The more sur- 
face the air touches, the more heat will it carry 
away; and so the Golt gun was at first made 
with a very thick-walled barrel. But later the 



48 INVENTIONS OF THE GREAT WAR 

Colt was formed with flanges, like the flanges 
on a motor-cycle engine, so as to increase the 
surface of the barrel. Of course, air-cooling is 
not so effective as water-cooling, but it is 
claimed for this gun, and for other machine- 
guns of the same class, that the barrel is 
sufficiently cooled for ordinary service. Al- 
though a machine-gun may be capable of firing 
many hundred shots per minute, it is seldom 
that such a rate is kept up very long in battle. 
Usually, only a few rounds are fired at a time 
and then there is a pause, and there is plenty 
of time for the barrel to cool. Once in a while, 
however, the gun has to be fired continuously 
for several minutes, and then the barrel grows 
exceedingly hot. 

EFFECT OF OVERHEATING 

But what if the gun-barrel does become hot? 
The real trouble is not that the cartridge will 
explode prematurely, but that the barrel will 
expand as it grows hot, so that the bullet will 
fit too loosely in the bore. Inside the barrel 
the bore is rifled; that is, there are spiral 
grooves in it which give a twist to the bullet 
as it passes through, setting it spinning like a 



GUNS THAT FIRE THEMSELVES 49 

top. The spin of the bullet keeps its nose point- 
ing forward. If it were not for the rifling, the 
bullet would tumble over and over, every which 
way, and it could not go very far through the 
air, to say nothing of penetrating steel armor. 
To gain the spinning-motion the bullet must 
fit into the barrel snugly enough to squeeze 
into the spiral grooves. Now there is another 
American machine-gun known as the Hotchkiss, 
which was used to a considerable extent by the 
French Army. It is a gas-operated gun, some- 
thing like the Colt, and it is air-cooled. It was 
found in tests of the Hotchkiss gun that in from 
three to four minutes of firing the barrel was 
expanded so much that the shots began to be a 
little uncertain. In seven minutes of con- 
tinuous firing the barrel had grown so large that 
the rifling failed to grip the bullet at all. The 
gun was no better than an old-fashioned 
smooth-bore. The bullets would not travel 
more than three hundred yards. It is because 
of this danger of overheating that the Colt and 
the Hotchkiss guns are always furnished with a 
spare barrel. As soon as a barrel gets hot it is 
uncoupled and the spare one is inserted in its 
place. Our men are trained to change the 



50 INVENTIONS OF THE GREAT WAR 

barrel of a colt in the dark in a quarter of a 
minute. 

But a gun that has to have a spare barrel 
and that has to have its barrel changed in the 
midst of a hot engagement is not an ideal 
weapon, by any means. And this brings us to 
still another invention — that, too, by an Amer- 
ican. Colonel I. N. Lewis, of the United States 
Army, conceived of a machine-gun that would be 
cooled not by still air but by air in motion. This 
would do away with all the bother of water- 
jackets. It would keep the gun light so that 
it could be operated by one man, and yet it 
would not have to be supplied with a spare 
barrel. 

Like the Colt and the Hotchkiss, the Lewis 
gun takes its power from the gas that comes 
through a small port in the barrel, near the 
muzzle. In the plate facing page 44 the port 
may be seen leading into a cylinder that lies 
under the barrel. It takes about one ten- 
thousandth part of a second for a bullet to 
pass out of the barrel after clearing the port, 
but in that brief interval there is a puff of 
gas in the cylinder which drives back a pis- 
ton. This piston has teeth on it which en- 






GUNS THAT FIRE THEMSELVES 51 

gage a small gear connected with a main- 
spring. When the piston moves back, it winds 
the spring, and it is this spring that operates 
the mechanism of the gun. The cartridges, in- 
stead of being taken from a belt or a clip, are 
taken from a magazine that is round and flat. 
There are forty-seven cartridges in the maga- 
zine and they are arranged like the spokes of a 
wheel, but in two layers. As soon as forty- 
seven rounds have been fired, the shooting must 
stop while a new magazine is inserted. But to 
insert it takes only a couple of seconds. 

USING THE BULLET TO FAN THE GUN 

The most ingenious part of the Lewis gun 
is the cooling-system. On the barrel of the gun 
arc sixteen flanges or fins. These, instead of 
running around the gun, run lengthwise of the 
barrel. They are very light fins, being made 
of aluminum, and are surrounded by a cas- 
ing of the same metal. The casing is open at 
each end so that the air can flow through it, 
but it extends beyond the muzzle of the barrel, 
and there it is narrowed down. At the end of 
the barrel there is a mouthpiece so shaped that 
the bullet, as it flies through, sucks a lot of air 



52 INVENTIONS OF THE GREAT WAR 

in its wake, making a strong current flow 
through the sixteen channels formed between 
the fins inside the casing. This air flows at the 
rate of about seventy miles per hour, which is 
enough to carry off all the heat that is generated 
by the firing of the cartridges. The gun may 
be regulated to fire between 350 and 750 rounds 
per minute, and its total weight is only 25% 
pounds. 

America can justly claim the honor of invent- 
ing and developing the machine-gun, although 
Hiram Maxim did give up his American citizen- 
ship and become a British subject. By the way, 
he is not to be confused with his younger 
brother, Hudson Maxim, the inventor of high 
explosives, who has always been an American 
to the core. Of course we must not get the im- 
pression that only Americans have invented 
machine-guns. There have been inventors of 
such weapons in various countries of Europe, 
and even in Japan. Our own army for a while 
used a gun known as the Benet-Mercie, which 
is something like the Hotchkiss. This was in- 
vented by L. V. Benet, an American, and H. A. 
Mercie, a Frenchman, both living in St. Denis, 
France. 



% 




Lewis Machine-guns in action at the front 



GUNS THAT FIRE THEMSELVES 53 

THE BROWNING MACHINE-GUN 

When we entered the war, it was expected 
that we would immediately equip our forces 
with the Lewis gun, because the British and the 
Belgians Irad found it an excellent weapon and 
also because it was invented by an American 
officer, who very patriotically offered it to our 
government without charging patent royalties. 
But the army officials would not accept it, 
although many Lewis guns were bought by the 
navy. This raised a storm of protest through- 
out the country until finally it was learned that 
there was another gun for which the army was 
waiting, which it was said would be the very 
best yet. The public was skeptical and finally 
a test was arranged in Washington at which the 
worth of the new gun was demonstrated. 

It was a new Browning model; or, rather, 
there were two distinct models. One of them, 
known as the heavy model, weighed only 34% 
pounds, this with its water-jacket filled; for it 
was a water-cooled gun. Without its charge of 
water the machine weighed but 22% pounds and 
could be rated as a very light machine-gun. 
However, it was classed as a heavy gun and was 



54 INVENTIONS OF ?HE GREAT WAR 

operated from a tripod. The new machine used 
recoil to operate its mechanism. - The construc- 
tion was simple, there were few parts, and the 
gun could very quickly be taken apart in case 
of breakage or disarrangement of the mechan- 
ism. But the greatest care was exercised to 
prevent jamming of cartridges, which was one 
of the principal defects in the other types of 
machine-guns. In the test this new weapon 
fired twenty thousand shots at the rate of six 
hundred per minute, with interruptions of only 
four and a half seconds, due partly to defective 
cartridges. 

There was no doubt that the new Browning 
was a remarkable weapon. But if that could 
be said of the heavy gun, the light gun was a 
marvel. It weighed only fifteen pounds and 
was light enough to be fired from the shoulder 
or from the hip, while the operator was walk- 
ing or running. In fact, it was really a ma- 
chine-rifle. The regular .30-caliber service 
cartridges were used, and these were stored in 
a clip holding twenty cartridges. The cart- 
ridges could be fired one at a time, or the entire 
clip could be fired in two and a half seconds. It 
took but a second to drop an empty clip out of 



GUNS THAT FIRE THEMSELVES 55 

the gun and replace it with a fresh one. The 
rifle was gas-operated and air-cooled, but no 
special cooling-device was supplied because it 
would seldom be necessary to fire a shoulder 
rifle fast enough and long enough for the barrel 
to become overheated. 

After the Browning machine-rifle was demon- 
strated it was realized that the army had been 
perfectly justified in waiting for the new 
weapon. Like the heavy Browning, the new 
rifle was a very simple mechanism, with few 
parts which needed no special tools to take them 
apart or reassemble them; a single small wrench 
served this purpose. Both the heavy and the 
light gun were proof against mud, sand, and 
dust of the battle-field. But best of all, a man 
did not have to have highly specialized training 
before he could use the Browning rifle. It did 
not require a crew to operate one of these guns. 
Each soldier could have his own machine-gun 
and carry it in a charge as he would a rifle. 
The advantage of the machine-rifle was that the 
operator could fire as he ran, watching where 
the bullets struck the ground by noting the dust 
they kicked up and in that way correcting his 
aim until he was on the target. Very accurate 



56 INVENTIONS OF THE GREAT WAR 

shooting was thus made possible, and the ma- 
chine-rifle proved invaluable in the closing 
months of the war. 

Browning is unquestionably the foremost in- 
ventor of firearms in the world. He was born 
of Mormon parents, in Ogden, Utah, in 1854, 
and his father had a gun shop. As a boy 
Browning became familiar with the use of fire- 
arms and when he was but fourteen years of 
age he invented an improved breech mechanism 
which was later used in the Winchester repeater. 
Curiously enough, it was a Browning pistol that 
was used by the assassin at Serajevo who killed 
the Archduke of Austria and precipitated the 
great European war, and it was with the Brown- 
ing machine-gun and rifle that our boys swept 
the Germans back through the Argonne For- 
est and helped to bring the war to a successful 
end. 

THE MACHINE-GUN IN SERVICE 

Although the machine-gun has been used ever 
since the Civil War, it was not a vital factor in 
warfare until the recent great conflict. Army 
officials were very slow to take it up, because 
they did not understand it. They used to think 



GUNS THAT FIRE THEMSELVES 57 

of it as an inferior piece of light artillery, in- 
stead of a superior rifle. The Gatling was so 
heavy that it had to be mounted on wheels, and 
naturally it was thought of as a cannon. In 
the Franco-Prussian War the French had a ma- 
chine-gun by which they set great store. It was 
called a mitrailleuse, or a gun for firing grape- 
shot. It was something like the Gatling. The 
French counted on this machine to surprise 
and overwhelm the Germans. But they made 
the mistake of considering it a piece of artil- 
lery and fired it from long range, so that it did 
not have a chance to show its worth. Only on 
one or two occasions was it used at close 
range, and then it did frightful execution. 
However, it was a very unsatisfactory machine, 
and kept getting out of order. It earned the 
contempt of the Germans, and later when the 
Maxim gun was offered to the German Army 
they would have none of it. They did not want 
to bother with "a toy cannon.'' 

It really was not until the war between Eus- 
sia and Japan that military men began to real- 
ize the value of the machine-gun. As the war 
went on, both the Eussians and the Japanese 
bought up all the machine-guns they could se- 



58 INVENTIONS OF THE GREAT WAR 

cure. They learned what could be done with 
the aid of barbed wire to retard the. enemy while 
the machine-guns mowed them down as they 
were trying to get through. 

A man with a machine-gun is worth a hun- 
dred men with rifles; such is the military esti- 
mate of the weapon. The gun fires so fast that 
after hitting a man it will hit him again ten 
times while he is falling to the ground. And 
so it does not pay to fire the gun continuously 
in one direction, unless there is a dense mass of 
troops charging upon it. Usually the machine- 
gun is swept from side to side so as to cover 
as wide a range as possible. It is played upon 
the enemy as you would play the hose upon the 
lawn, scattering a shower of lead among the 
advancing hosts. 

MACHINE-GUN FORTS 

It used to be thought that the Belgian forts of 
armored steel and concrete, almost completely 
buried in the ground, would hold out against 
any artillery. But when the Germans brought 
up their great howitzers and hurled un- 
dreamed-of quantities of high explosives on 
these forts, they broke and crumbled to pieces. 



GUNS THAT FIRE THEMSELVES 59 

Then it was predicted that the day of the fort 
was over. But the machine-gun developed a 
new type of warfare. Instead of great forts, 
mounting huge guns, little machine-gun forts 
were built, and, they were far more troublesome 
than the big fellows. 

To the Germans belongs the credit for the new 
type of fort, which consisted of a small concrete 
structure, hidden from view as far as possible, 
but commanding some important part of the 
front. "Pill-boxes," the British call them, be- 
cause the first ones they ran across were round 
in shape and something like a pill-box in ap- 
pearance. These pill-boxes were just large 
enough to house a few men and a couple of 
machine-guns. Concealment was of the utmost 
importance; safety depended upon it. Air- 
planes were particularly feared, because a ma- 
chine-gun emplacement was recognized to be 
so important that a whole battery of artillery 
would be turned upon a suspected pill-box. 

Some of the German machine-gun forts were 
very elaborate, consisting of spacious under- 
ground chambers where a large garrison of 
gunners could live. These forts were known 
as Mebus, a word made from the initials of 



60 INVENTIONS OF THE GREAT WAR 

" Maschinengewehr Eisen-Bettungs Unter- 
stand," meaning a machine-gun- iron-bedded 
foundation. 

It was the machine-gun that was responsible 
for the enormous expenditure of ammunition in 
the war. Before a body of troops dared to 
make a charge, the ground had to be thoroughly 
searched by the big guns for any machine-gun 
nests. Unless these were found and destroyed 
by shell-fire, the only way that remained to get 
the best of them was to crush them down with 
tanks. It was really the machine-gun that 
drove the armies into trenches and under the 
ground. 

But a machine-gun did not have to be housed 
in a fort, particularly a light gun of the Lewis 
type. To be sure, the Lewis gun is a little 
heavy to be used as a rifle, but it could easily 
be managed with a rest for the muzzle in the 
crotch of a tree, and a strong man could actually 
fire the piece from the shoulder. The light ma- 
chine-gun could go right along with a charging 
body of troops and do very efficient service, par- 
ticularly in fighting in a town or village, but it 
had to be kept moving or it would be a target 
for the artillery. In a certain village fight a 






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GUNS THAT FIRE THEMSELVES 61 

machine-gunner kept changing his position. 
He would fire for a few minutes from one build- 
ing and then shift over to some other. He did 
this no less than six times, never staying more 
than five minutes at a time in the same spot. 
But each one of the houses was shelled within 
fifteen minutes of the time he opened fire from 
it, which shows the importance that the Ger- 
mans attached to machine-gun fire. 



CHAPTER IV 

Guns and Super-Guns 

WHEN the news came that big shells were 
dropping into Paris from a gun which 
must be at least seventy miles away, the world 
at first refused to believe; then it imagined 
that some brand-new form of gun or shell 
or powder had been invented by the Germans. 
However, while the public marveled, ordnance 
experts were interested but not astonished. 
They knew that it was perfectly feasible to build 
a gun that would hurl a shell fifty, or seventy- 
five, or even a hundred miles, without involving 
anything new in the science of gunnery. 

SHOOTING AEOUND THE EDGE OF THE EARTH 

But if such ranges were known to be possible, 
why was no such long-distance gun built before? 
Simply because none but the Germans would 
ever think of shooting around the edge of the 
earth at a target so far away that it would 

62 



GUNS AND SUPER-GUNS 63 

have- to be as big as a whole city to be hit at 
all. In a distance of seventy miles, the curve 
of 'the earth is considerable. Paris is far be- 
low the horizon of a man standing at St. Go- 
bain, where the big German gun was located. 
And if a hole were bored from St. Gobain 
straight to Paris, so that you could see the city 
from the gun, it would pass, midway of its 
course, -three- thousand, seven hundred and fifty 
feet below the surface of the earth. With the 
target so far off, it was impossible to aim at any 
particular fort, ammunition depot, or other 
point of military importance. There is always 
some uncertainty as to just where a shell will 
fall, due to slight differences in quality and 
quantity of the powder used, in the density of 
the air, the direction of the wind, etc. This 
variation is bad enough when a shell is to be 
fired ten miles, but when the missile has to 
travel seventy miles, it is out of the question 
to try to hit a target that is not miles in extent. 
Twenty years before the war our Ordnance 
Department had designed a fifty-mile gun, but 
it was not built, because we could see no possi- 
ble use for it. Our big guns were built for fight- 
ing naval battles or for the defense of our coasts 



64 INVENTIONS OF THE GREAT WAR 

from naval attacks, and there is certainly no use 
in firing at a ship that is so far below the horizon 
that we cannot even see the tips of its masts; 
and so our big guns, though they were capable 
of firing a shell twenty-seven miles, if aimed 
high enough, were usually mounted in carriages 
that would not let them shoot more than twelve 
or fifteen miles. 

The distance to which a shell can be hurled 
depends to a large extent upon the angle of the 
gun. If the gun is tilted up to an angle of 15 
degrees, the shell will go only about half as 
far as if it were tilted up to 43% degrees, which 
is the angle that will carry a shell to its great- 
est distance. If the long-range German gun 
was fired at that angle, the shell must have 
risen to a height of about twenty-four miles. 

BEYOND THE EAETH ? S ATMOSPHEEE 

Most of the air that surrounds our globe lies 
within four miles of the surface. Few airplanes 
can rise to a greater height than this, because 
the air is so thin that it gives no support to the 
wings of the machine. The greatest height to 
which a man has ever ascended is seven miles. 
A balloon once carried two men to such a height. 



GUNS AND SUPER-GUNS 65 

One of them lost consciousness, and the other, 
who was nearly paralyzed, succeeded in pulling 
the safety-valve rope with his teeth. That 
brought the balloon down, and their instruments 
showed that they had gone up thirty-six thou- 
sand feet. What the ocean of air contains above 
that elevation, we do not know, but judging by 
the way the atmosphere thins out as we rise 
from the surface of the earth, we reckon that 
nine tenths of the air lies within ten miles of 
the surface of the earth. At twenty-four miles, 
or the top of the curve described by the shell 
of the German long-range guns, there must be 
an almost complete vacuum. 

If only we could accompany a shell on its 
course, we should find a strange condition of 
affairs. The higher we rose, the darker would 
the heavens become, until the sun would shine 
like a fiery ball in a black sky. All around, the 
stars would twinkle, and below would be the 
glare of light reflected from the earth's surface 
and its atmosphere, while the cold would be far 
more intense than anything suffered on earth. 
Up at that height, there would be nothing to in- 
dicate that the shell was moving — no rush of 
air against the ears. We should seem detached 



66 INVENTIONS OF THE GREAT WAR 

from earth and out in the endless reaches of 
space. 

It seems absurd to think that a shell weighing 
close to a quarter of a ton could be retarded 
appreciably by mere air. But when we realize 
that the shell left the gun at the rate of over 
half a mile a second — traveling about thirty 
times faster than an express-train — we know 
that the air-pressure mounts up to a respectable 
figure. The pressure is the same whether a 
shell is moving through the air or the air is 
blowing against the shell. When the wind 
blows at the rate of 100 to 120 miles per hour, 
it is strong enough to lift houses off their foun- 
dations, to wrench trees out of the ground, to 
pick up cattle and carry them sailing through 
the air. Imagine what it would do if its ve- 
locity were increased to 1,800 miles per hour. 
That is what the shell of a big gun has to con- 
tend with. As most of the air lies near the 
earth, the shell of long-range guns meet with 
less and less resistance the higher they rise, 
until they get up into such thin air that there 
is virtually no obstruction. The main trouble 
is to pierce the blanket of heavy air that lies 
near the earth. 



GUNS AND SUPER-GUNS 67 

WAYS OF INCREASING THE RANGE 

The big 16-inch guns that protect our coasts 
fire a shell that weighs 2,400 pounds. Nine 
hundred pounds of smokeless powder is used to 
propel the shell, which leaves the muzzle of the 
gun with a speed of 2,600 feet per second. Now, 
the larger the diameter of the shell, the greater 
will be its speed at the muzzle of the gun, be- 
cause there will be a greater surface for the 
powder gases to press against. On the other 
hand, the larger the shell, the more will it' be 
retarded by the air, because there will be a 
larger surface for the air to press against. It 
has been proposed by some ordnance experts 
that a shell might be provided with a disk at 
each end, which would make it fit a gun of larger 
caliber. A 10-inch shell, for instance, could 
then be fired from a 16-inch gun. Being lighter 
than the 16-inch shell, it would leave the muzzle 
of the gun at a higher speed. The disks could 
be so arranged that as soon as the shell left 
the gun they would be thrown off, and then the 
10-inch shell, although starting with a higher 
velocity than a 16-inch shell, would offer less 
resistance to the air. In that way it could be 



68 INVENTIONS OF THE GREAT WAR 

made to cover a much greater range. By the 
way, the shell of the German- long-range gun 
was of but 8.2-inch caliber. 

Another way of increasing the range is to 
lengthen the gun. Eight here we must become 
acquainted with the word "caliber." Caliber 
means the diameter of the shell. A 16-inch gun, 
for instance, fires a shell of 16-inch caliber ; but 
when we read that the gun is a 40- or 50-caliber 
gun, it means that the length of the gun is forty 
or fifty times the diameter of the shell. Our 
biggest coast-defense guns are 50-caliber 16- 
inch guns, which means that they are fifty times 
16 inches long, or 66 2 A feet in length. When a 
gun is as long as that, care has to be taken to 
prevent it from sagging at the muzzle of its own 
weight. These guns actually do sag a little, 
and when the shell is fired through the long 
barrel it straightens up the gun, making the 
muzzle "whip" upward, just as a drooping 
garden hose does when the water shoots through 
it. 

Now the longer the caliber length of a gun, 
the farther it will send a shell, because the pow- 
der gases will have a longer time to push the 
shell. But we cannot lengthen our big guns 



GUNS AND SUPEE-GUNS M 

much more without using some special support 
for the muzzle end of the gun, to keep it from 
u whipping' ' too much. It is likely that the 
long-range German gun was provided with a 
substantial support at the muzzle to keep it 
from sagging. 

Every once in a while a man comes forth with 
a "new idea" for increasing the range. One 
plan is to increase the powder-pressure. We 
have powders that will produce far more pres- 
sure than an ordinary gun can stand. But we 
have to use powders that will burn compara- 
tively slowly. We do not want too sudden a 
shock to start with, but we wish the powder 
to give off an enormous quantity of gas which 
will keep on pushing and speeding up the shell 
until the latter emerges from the muzzle. The 
fifty-mile gun that was proposed twenty years 
ago was designed to stand a much higher pres- 
sure than is commonly used, and it would have 
fired a 10-inch shell weighing 600 pounds with 
a velocity of 4,000 feet per second at the muzzle. 

The Allies built no " super-guns,' ' because 
they knew that they could drop a far greater 
quantity of explosives with much greater ac- 
curacy from airplanes, and at a much lower 



70 INVENTIONS OF THE GREAT WAR 

cost. The German gun at St. Gobain was spec- 
tacular and it did some damage, but it bad no 
military value and it did not intimidate the 
French as the Germans had hoped it would. 

A GUN WITH A KANGE OF A HUNDEED AND 
TWENTY MILES 

But although we built no such gun, after the 
Germans began shelling Paris our Ordnance 
Department designed a gun that would fire a 
shell to a distance of over 120 miles! There 
was no intention of constructing the gun, but 
the design was worked out just as if it were 
actually to be built. It was to fire a shell of 
10-inch caliber, weighing 400 pounds. Now, an 
Elswick standard 10-inch gun is 42 feet long 
and its shell weighs 500 pounds. Two hundred 
pounds of powder are used to propel the shell, 
which leaves the muzzle with a velocity of 3,000 
feet per second. If the gun is elevated to the 
proper angle, it will send the shell 25 miles, and 
it will take the shell a minute and thirty-seven 
seconds to cover that distance. But the long- 
range gun our ordnance experts designed would 
have to be charged with 1,440 pounds of powder 
and the shell would leave the muzzle of the gun 



GUNS AND SUPER-GUNS 71 

with a velocity of 8,500 feet per second. It 
would be in the air four minutes and nine sec- 
onds and would travel 121.3 miles. "Were the 
gun fired from the Aberdeen Proving Grounds, 
near Baltimore, Maryland, its shell would travel 
across three states and fall into New York Bay 
at Perth Amboy. At the top of its trajectory 
it would rise 46 miles above the earth. 

But the most astonishing part of the design 
was the length of the gun, which worked out to 
225 feet. An enormous powder-chamber would 
have to be used, so that the powder gases would 
keep speeding up the shell until it reached the 
required velocity at the muzzle. The weight 
of the barrel alone was estimated at 325 tons. 

It would have to be built up in four sections 
screwed together and because of its great 
length and weight it would have to be supported 
on a steel truss. The gun would be mounted 
like a roller lift-bridge with a heavy counter- 
weight at its lower end so that it could be ele- 
vated or depressed at will and a powerful hy- 
draulic jack would be required to raise it. 

The recoil 'of a big gun is always a most im- 
portant matter. Unless a gun can recoil, it 
will be smashed by the shock of the powder ex- 



72 INVENTIONS OF THE GREAT WAR 

plosion. Usually, heavy springs are used to 
take up the shock, or cylinders filled with oil in 
which pistons slide. The pistons have small 
holes in them through which the oil is forced 
as the piston moves and this retards the gun 
in its recoil. But this "super-gun" was de- 
signed to be mounted on a carriage running 
on a set of tracks laid in a long concrete pit. 
On the recoil the gun would run back along 
the tracks, and its motion would be retarded by 
friction blocks between the carriage and the 
tracks and also by a steel cable attached to the 
forward end of the carriage and running over 
a pulley on the front wall of the pit, to a fric- 
tion drum. 

The engraving facing page 68 gives some idea 
of the enormous size of the gun. Note the man 
at the breech of the gun. The hydraulic jack 
is collapsible, so that the gun may be brought 
to the horizontal position for loading, as shown 
by the dotted lines. The cost of building this 
gun is estimated at two and a half million dol- 
lars and its 400-pound shell would land only 
about sixty pounds of high explosives on the 
target. A bombing-plane costing but thirty 
thousand dollars could land twenty-five times? 



GUNS AND SUPER-GUNS 73 

as big a charge of high explosives with far 
greater accuracy. Aside from this, the gun 
lining would soon wear out because of the tre- 
mendous erosion of the powder gases. 

THE THREE-SECOND LIFE OF A GUN 

Powder gases are very hot indeed — hot 
enough to melt steel. The greater the pressure 
in the gun, the hotter they are. It is only be- 
cause they pass through the gun so quickly, 
that they do not melt it. As a matter of fact, 
they do wear it out rapidly because of their 
heat and velocity. They say that the life of a 
big gun is only three seconds. Of course, a shell 
passes through the gun in a very minute part 
of a second, but if we add up these tiny periods 
until we have a total of three seconds, during 
which the gun may have fired two hundred 
rounds, we shall find that the lining of the barrel 
is so badly eroded that the gun is unfit for ac- 
curate shooting, and it must go back to the shops 
for a new inner tube. 

ELASTIC GUNS 

We had better go back with it and learn 
something about the manufacture of a big gun. 



74 INVENTIONS OF THE GREAT WAR 

Guns used to be cast as a solid chunk of metal. 
Now they are built up in layers. To under- 
stand why this is necessary, we must realize 
that steel is not a dead mass, but is highly elas- 
tic — far more elastic than rubber, although, of 
course, it does not stretch nor compress so far. 
When a charge of powder is exploded in the 
barrel of a gun, it expands in all directions. 
Of course, the projectile yields to the pressure 
of the powder gases and is sent kiting out of the 
muzzle of the gun. But for an instant before 
the shell starts to move, an enormous force is 
exerted against the walls of the bore of the 
gun, and, because steel is elastic, the barrel is 
expanded by this pressure, and the bore is ac- 
tually made larger for a moment, only to spring 
back in the next instant. You can picture this 
action if you imagine a gun made of rubber; 
as soon as the powder was fired, the rubber 
gun would bulge out around the powder-cham- 
ber, only to collapse to its normal size when 
the pressure was relieved by the discharge of 
the bullet. 

Now,, every elastic body has what is called its 
elastic limit. If you take a coil spring, you can 
pull it out or you can compress it, and it will 



GUNS AND SUPER-GUNS 75 

always return to its original shape, unless you 
pull it out or compress it beyond a certain 
point ; that point is its elastic limit. The same 
is true of a piece of steel: if you stretch it be- 
yond a certain point, it will not return to its 
original shape. When the charge of powder 
in a cannon exceeds a certain amount, it 
stretches the steel beyond its elastic limit, so 
that the bore becomes permanently larger. 
Making the walls of the gun heavier would not 
prevent this, because steel is so elastic that the 
inside of the walls expands beyond its elastic 
limit before the outside is affected at all. 

Years ago an American inventor named 
Treadwell worked out a scheme for allowing the 
bore to expand more without exceeding its elas- 
tic limit. He built up his gun in layers, and 
shrunk the outer layers upon the inner layers, 
just as a blacksmith shrinks a tire on a wheel, 
so that the inner tube of the gun would be 
squeezed, or compressed. When the powder 
was fired, this inner layer could expand farther 
without danger, because it was compressed to 
start with. The built-up gun was also indepen- 
dently invented by a British inventor. All 
modern big guns are built up. 



76 INVENTIONS OF THE GREAT WAR 

HOW BIG GUNS ARE MADE 

The inside tube, known as the lining, is cast 
roughly to shape, then it is bored out, after 
which it is forged by the blows of a powerful 
steam-hammer. Of course, while under the 
hammer, the tube is mounted on a mandrel, or 
bar, that just fits the bore. The metal is then 
softened in an annealing furnace, after which 
it is turned down to the proper diameter and re- 
bored to the exact caliber. The diameter of 
the lining is made three ten-thousandths of an 
inch larger than the inside of the hoop or sleeve 
that fits over it. This sleeve, which is formed 
in the same way, is heated up to 800 degrees, 
or until its inside diameter is eight tenths of an 
inch larger than the outside diameter of the 
lining. The lining is stood up on end and the 
sleeve is fitted over it. Then it is cooled by 
means of water, so that it grips the lining and 
compresses it. In this way, layer after layer 
is added until the gun is built up to the proper 
size. 

Instead of having a lining that is compressed 
by means of sleeves or jackets, many big guns 
are wound with wire which is pulled so tight as 



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GUNS AND SUPER-GUNS 77 

to compress the lining. The gun-tube is placed 
in a lathe, and is turned so as to wind up the wire 
upon it. A heavy brake on the wire keeps it 
drawn very tight. This wire, also, is put on in 
layers, so that each layer can expand consid- 
erably without exceeding its elastic limit. Our 
big 16-inch coast-defense guns are wound with 
wire that is one tenth of an inch square. The 
length of wire on one gun is sufficient to reach 
all the way from New York to Boston with fifty 
or sixty miles of wire left over, 

GUNS THAT PLAY HIDE-AND-SEEK 

A very ingenious invention is the disappear- 
ing-mount which is used on our coast fortifica- 
tions. By means of this a gun is hidden beyond 
its breastworks so that it is absolutely invisible 
to the enemy. In this sheltered position it is 
loaded and aimed. It is not necessary to sight 
the gun on the target as you would sight a rifle. 
The aiming is done mathematically. Off at 
some convenient observation post, an observer 
gets the range of the target and telephones this 
range to the plotting-room, where a rapid cal- 
culation is made as to how much the gun should 
be elevated and swung to the right or the left. 



78 INVENTIONS OF THE GREAT WAR 

This calculation is then sent on to the gunners, 
who adjust the gun accordingly. When all is 
ready, the gun is raised by hydraulic pressure, 
and just as it rises above the parapet it is auto- 
matically fired. The recoil throws the gun back 
to its crouching position behind the breastworks. 
All that the enemy sees, if anything, is the flash 
of the discharge. 

Now that airplanes have been invented, the 
disappearing-mount has lost much of its useful- 
ness. Big guns have to be hidden from above. 
They are usually located behind a hill, five or six 
miles back of the trenches, where the enemy can- 
not see them from the ground, and they are care- 
fully hidden under trees or a canopy of foliage 
or are disguised with paint. 

The huge guns recently built to defend our 
coasts are intended to fire a shell that will pierce 
the heavy armor of a modern dreadnought. 
The shell is arranged to explode after it has 
penetrated the armor, and the penetrating- 
power is a very important matter. About 
thirty years ago the British built three battle- 
ships, each fitted w T ith two guns of 16%-inch cali- 
ber and 30-caliber length. In order to test the 
penetrating-pow T er of this gun a target was 



GUNS AND SUPER-GUNS 79 

built, consisting first of twenty inches' of steel 
armor and eight inches of wrought-iron ; this 
was backed by twenty feet of oak, five feet of 
granite, eleven feet of concrete, and six feet 
of brick. When the shell struck this target it 
passed through the steel, the iron, the oak, the 
granite, and the concrete, and did not stop until 
it had penetrated three feet of the brick. We 
have not subjected our 16-inch gun to such a 
test, but we know that it would go through two 
such targets and still have plenty of energy left. 
Incidentally, it costs us $1,680 each time the big 
gun is -fired. 

THE FAMOUS FORTY-TWO-CENTIMETER GUN 

One of the early surprises of the war was the 
huge gun used by the Germans to destroy the 
powerful Belgian forts. Properly speaking, 
this was not a gun, but a howitzer; and right 
here we must learn the difference between mor- 
tars, howitzers, and guns. What we usually 
mean by "gun" is a piece of long caliber which 
is designed to hurl its shell with a flat trajec- 
tory. But long ago it was found advantageous 
to throw a projectile not at but upon a fortifica- 
tion, and for this purpose short pieces of large 



80 INVENTIONS OF THE GREAT WAR 

bore were built. These would fire at a high 
angle, so that the projectile would fall almost 
vertically on the target. 

As we have said, the bore of a gun is rifled ; 
that is, it is provided with spiral grooves that 
will set the shell spinning, so as to keep its 
nose pointing in the direction of its flight. 
Mortars, on the other hand, were originally in- 
tended for short-range firing, and their bore 
was not rifled. In recent years, however, mor- 
tars have been made longer and with rifled 
bores, so as to increase their range, and such 
long mortars are called ' i howitzers. ' ' The Ger- 
man 42-centimeter howitzer fired a shell that was 
2,108 pounds in weight and was about 1% yards 
long. The diameter of the shell was 42 centi- 
meters, which is about 16% inches. It carried 
an enormous amount of high explosive, which 
was designed to go off after the shell had 
penetrated its target. The marvel of this how- 
itzer was not that it could fire so big a shell but 
that so large a piece of artillery could be trans- 
ported over the highroads and be set for use in 
battle. But although the 42-centimeter gun was 
widely advertised, the real work of smashing 
the Belgian forts was done by the Austrian 



GUNS AND SUPER-GUNS 81 

"Skoda" howitzers, which fired a shell of 30.5- 
centimeter (12-inch) caliber, and not by the 42- 
centimeter gun. The Skoda howitzer could be 
taken apart and transported by three motor- 
cars of 100 horse-power each. The cars trav- 
eled at a rate of about twelve miles per hour. 
It is claimed the gun could be put together in 
twenty-four minutes, and would fire at the rate 
of one shot per minute. 

FIELD-GUNS 

So far, we have talked only of the big guns, 
but in a modern battle the fieM-gun plays a very 
important part. This fires a shell that weighs 
between fourteen and eighteen pounds and is 
about three inches in diameter. The shell and 
the powder that fires it are contained in a cart- 
ridge that is just like the cartridge of a shoul- 
der rifle. These field-pieces are built to be fired 
rapidly. The French 75-millimeter gun, which 
is considered one of the best, will fire at the 
rate of twenty shots per minute, and its effective 
range is considerably over three miles. The 
French supplied us with all 75-millimeter guns 
we needed in the war, while we concentrated 
our efforts on the manufacture of ammunition. 



82 INVENTIONS OF THE GREAT WAR 



GUNS THAT FIRE GUNS 

During the War of the Bevolution, cannon 
were fired at short range, and it was the cus- 
tom to load them with grape-shot, or small iron 
balls, when firing against a charging enemy, be- 
cause the grape would scatter like the shot of 
a shot-gun and tear a bigger gap in the ranks of 
the enemy than would a single solid cannon-ball. 
In modern warfare, guns are fired from a 
greater distance, so that there will be little dan- 
ger of their capture. It is impossible for them 
to fire grape, because the ranges are far too 
great; besides, it would be impossible to aim a 
charge of grape-shot over any considerable dis- 
tance, because the shot would start spreading as 
soon as they left the muzzle of the gun and 
would scatter too far and wide to be of much 
service. But this difficulty has been overcome 
by the making of a shell which is really a gun in 
itself. Within this shell is the grape-shot, 
which consists of two hundred and fifty half- 
inch balls of lead. The shell is fired over the 
lines of the enemy, and just at the right moment 
it explodes and scatters a hail of leaden balls 
over a fairly wide area. 



GUNS AND SUPER-GUNS 83 

It is not a simple matter to time a shrapnel 
shell so that it will explode at jnst the right mo- 
ment. Spring-driven clockwork has been tried, 
which would explode a cap after the lapse of a 
certain amount of time ; but this way of timing 
shells has not proved satisfactory. Nowadays 
a train of gunpowder is used. When the shell 
is fired, the shock makes a cap (see drawing fac- 
ing page 77) strike a pin, E, which ignites the 
train of powder, A. The head of the shell is 
made of two parts, in each of which there is a 
powder-fuse. There is a vent, or short cut, 
leading from one fuse to the other, and, by the 
turning of one part of the fuse-head with respect 
to the other, this short cut is made to carry the 
train of fire from the upper to the lower fuse 
sooner or later, according to the adjustment. 
The fire burns along one powder-train A, and 
then jumps through the short cut B to the other, 
or movable train, as it is called, until it finally 
reaches, through hole C, the main charge F, in 
the shell. The movable part of the fuse-head is 
graduated so that the fuse may be set to explode 
the shell at any desired distance. In the fuse- 
head there is also a detonating-pin K, which 
will strike the primer L and explode the shell 



84 INVENTIONS OF THE GREAT WAR 

when the latter strikes the ground, if the time- 
fuse has failed to act. 

When attacking airplanes, it is important to 
be able to follow the flight of the shell, so some 
shrapnel shell are provided with a smoke-pro- 
ducing mixture, which is set on fire when the 
shell is discharged, so as to produce a trail of 
smoke. 

In meeting the attack of any enemy at night, 
search-light shell are sometimes used. On ex- 
ploding they discharge a number of "candles," 
each provided with a tiny parachute that lets 
the candle drop slowly to the ground. Their 
brilliant light lasts fifteen or twenty minutes. 
Obviously, ordinary search-lights could not be 
used on the battle-field, because the lamp would 
at once be a target for enemy batteries, but with 
search-light shell the gun that fires them can 
remain hidden and one 's own lines be shrouded 
in darkness while the enemy lines are brilliantly 
illuminated. 



CHAPTER V 

The Battle of the Chemists 

SOME years ago the nations of the world 
gathered at the city of The Hague, in Hol- 
land^ to see what could be done to put an end to 
war. They did not accomplish much in that di- 
rection, but they did draw up certain rules of 
warfare which they agreed to abide by. There 
were some practices which were considered too 
horrible for any civilized nation to indulge in. 
Among these was the use of poisonous gases, 
and Germany was one of the nations that took 
a solemn pledge not to use gas in war. 

Eighteen years later the German Army had 
dug itself into a line of trenches reaching from 
the English Channel to Switzerland, and facing 
them in another line of trenches were the armies 
of France and England, determined to hold back 
the invaders. Neither side could make an ad- 
vance without frightful loss of life. But a 
German scientist came forth with a scheme for 

85 



86 INVENTIONS OF THE GREAT WAR 

breaking the dead-lock. This was Professor 
Nernst, the inventor of a well-known electric 
lamp and a man who had always violently hated 
the British. His plan was to drown out the 
British with a flood of poisonous gas. To be 
sure, there was the pledge taken at The Hague 
Conference, but why should that stand in Ger- 
many's way? What cared the Germans for 
promises now? Already they had broken a 
pledge in their violation of Belgium. Already 
they had rained explosives from the sky on un- 
fortified British cities (thus violating another 
pledge of The Hague Conference) ; already they 
had determined to war on defenseless merchant- 
men. To them promises meant nothing, if such 
promises interfered with the success of German 
arms. They led the world in the field of chem- 
istry ; why, they reasoned, should n't they make 
use of this advantage? 

POURING GAS LIKE WATER 

It was really a new mode of warfare that the 
Germans were about to launch and it called for 
much study. In the first place, they had to de- 
cide what sort of gas to use. It must be a gas 
that could be obtained in large quantities. It 



THE BATTLE OF THE CHEMISTS 87 

must be a very poisonous gas, that would act 
quickly on the enemy; it must be easily com- 
pressed and liquefied so that it could be carried 
in containers that were not too bulky; it must 
vaporize when the pressure was released; and 
it must be heavier than air, so that it would not 
be diluted by the atmosphere but would hug the 
ground. You can pour gas just as you pour 
water, if it is heavier than air. A heavy gas 
will stay in the bottom of an unstoppered bottle 
and can be poured from one bottle into another 
like water. If the gas is colored, you can see 
it flowing just as if it were a liquid. On the 
other hand, a gas which is much lighter than 
air can also be kept in unstoppered bottles if 
the bottles are turned upside down, and the gas 
can be poured from one bottle into another ; but 
it flows up instead of down. 

Chlorine gas was selected because it seemed 
to meet all requirements. For the gas attack 
a point was chosen where the ground sloped 
gently toward the opposing lines, so that the 
gas would actually flow down hill into them. 
Preparations were carried out with the utmost 
secrecy. Just under the parapet of the trenches 
deep pits were dug, about a yard apart on a 



§8 INVENTIONS OF THE GREAT WAR 

front of fifteen miles, or over twenty-five thou- 
sand pits. In these pits were placed the chlo- 
rine tanks, each weighing about ninety pounds. 
Each pit was then closed with a plank and this 
was covered with a quilt filled with peat moss 
soaked in potash, so that in case of any leakage 
the chlorine would be taken up by the potash 
and rendered harmless. Over the quilts sand- 
bags were piled to a considerable height, to 
protect the tanks from shell-fragments. 

Liquid chlorine will boil even in a tempera- 
ture of 28 degrees below zero Fahrenheit, but 
in tanks it cannot boil because there is no room 
for it to turn into a gas. Upon release of the 
pressure at ordinary temperatures, the liquid 
boils violently and big clouds of gas are pro- 
duced. If the gas were tapped off from the top 
of the cylinder, it would freeze on pouring out, 
because any liquid that turns into a gas has to 
draw heat from its surroundings. The greater 
the expansion, the more heat the gas absorbs, 
and in the case of the chlorine tanks, had the 
nozzles been set in the top of the tank they 
would very quickly have been crusted with frost 
and choked, stopping the flow. 

But the Germans had anticipated this dim- 



THE BATTLE OF THE CHEMISTS 89 

culty, and instead of drawing off the gas from 
the top of the tank, they drew off the liquid 
from the bottom in small leaden tubes which 
passed up through the liquid in the tank and 
were kept as warm as the surrounding liquid. 
In fact, it was not gas from the top of the tank, 
but liquid from the bottom, that was streamed 
out and this did not turn into gas until it had 
left the nozzle. 

WAITING FOR THE WIND 

Everything was ready for the attack on the 
British in April, 1915. A point had been chosen 
where the British lines made a juncture with 
the French. The Germans reckoned that a 
joint of this sort in the opponent's lines would 
be a spot of weakness. Also, they had very 
craftily picked out this particular spot because 
the French portion of the line was manned by 
Turcos, or Algerians, who would be likely to 
think there was something supernatural about 
a death-dealing cloud. On the left of the Afri- 
cans was a division of Canadians, but the main 
brunt of the gas was designed to fall upon the 
Turcos. Several times the attack was about 
to be made, but was abandoned because the 



90 INVENTIONS OF THE GREAT WAR 

wind was not just right. The Germans wished 
to pick out a time when the breeze was blowing 
steadily — not so fast as to scatter the gas, but 
yet so fast that it would overtake men who at- 
tempted to run away from it. It was not until 
April 22 that conditions were ideal, and then 
the new mode of warfare was launched. 

Just as had been expected, the Turcos were 
awe-struck when they saw, coming out of the 
German trenches, volumes of greenish-yellow 
gas, which rolled toward them, pouring down 
into shell-holes and flowing over into the 
trenches as if it were a liquid. They were 
seized with superstitious fear, particularly when 
the gas overcame numbers of them, stifling 
them and leaving them gasping for breath. Im- 
mediately there was a panic and they raced 
back, striving to out-speed the pursuing 
cloud. 

For a stretch of fifteen miles the Allied 
trenches were emptied, and the Germans, who 
followed in the wake of the gas, met with no op- 
position except in the sector held by the Cana- 
dians. Here, on the fringe of the gas cloud, so 
determined a fight was put up that the Germans 
faltered, and the brave Canadians held them 



THE BATTLE OF THE CHEMISTS 91 

until reinforcements arrived and the gap in the 
line was closed. 

The Germans themselves were new at the 
game or they could have made a complete suc- 
cess of this surprise attack. Had they made the 
attack on a broader front, nothing could have 
kept them from breaking through to Calais. 
The valiant Canadians who struggled and 
fought without protection in the stifling clouds 
of chlorine, were almost wiped out. But many 
of them who were on the fringe of the cloud es- 
caped by wetting handkerchiefs, socks, or other 
pieces of cloth, and wrapping them around their 
mouths and noses. 

The world was horrified when it read of this 
German gas attack, but there was no time to be 
lost. Immediately orders went out for gas- 
masks, and in all parts of England, and of 
France as well, women were busy sewing the 
masks. These were very simple affairs — 
merely a pad of cotton soaked in washing-soda 
and arranged to be tied over the mouth and nose. 
But when the next attack came, not long after 
the first, the men were prepared in some meas- 
ure for it, and again it failed to bring the Ger- 
mans the success they had counted upon. 



92 INVENTIONS OF THE GREAT WAR 

One thing that the Germans had not counted 
upon was the fact that the prevailing winds in 
Flanders blow from west to east. During the 
entire summer and autumn of 1915, the winds 
refused to favor them, and no gas attacks were 
staged from June to December. This gave the 
British a long respite and enabled them not only 
to prepare better gas-masks, but also to make 
plans to give the Hun a dose of his own medi- 
cine. 

WHEN THE WIND PLAYED A TRICK ON THE GERMANS 

There were many disadvantages in the use 
of gas clouds, which developed as the Germans 
gathered experience. The gas started from 
their own lines in a very dense cloud, but the 
cloud grew thinner and thinner as it traveled 
toward the enemy, and lost a great deal of its 
strength. If the wind were higher than fifteen 
miles an hour, it would swirl the gas around and 
dissipate it before it did much harm to the op- 
posing fighters. If the wind were light, there 
were other dangers. On one occasion in 1916 
a cloud of gas was released upon an Irish regi- 
ment. The wind was rather fickle. It carried 
the gas toward the British trenches, but before 



iiilliii;:,.. Km^rnm 



':;:'•; : 





Courtesy of "Scientific American " 

Cleaning Up a Dugout with the "Fire Broom 



THE BATTLE OF THE CHEMISTS 93 

reaching them the cloud hesitated, the wind 
veered around, and soon the gas began to pour 
back upon the German lines. The Germans 
were entirely unprepared for this boomerang 
attack. Many of the Huns had no gas-masks 
on, and those who had, found that the masks 
were not in proper working-order. As a result 
of this whim of the winds, eleven thousand Ger- 
mans were killed. 

While chlorine was the first gas used, it was 
evident that it was not the only one that could 
be employed. British chemists had suspected 
that the Germans would use phosgene, which 
was a much more deadly gas, and in the long in- 
terval between June and December, 1915, masks 
were constructed which would keep out not only 
the fumes of chlorine but also the more poison- 
ous phosgene. In one of their sorties the Brit- 
ish succeeded in capturing some valuable notes 
on gas attacks, belonging to a German general, 
which showed that the Germans were actually 
preparing to use phosgene. This deadly gas is 
more insidious in its action than chlorine. The 
man who inhales phosgene may not know that 
he is gassed. He may experience no ill effects, 
but hours afterward, particularly if he has ex- 



94 INVENTIONS OF THE GREAT WAR 

ercised in the meantime, he may suddenly fall 
dead, owing to its paralyzing action on the heart. 

FREEING THE BRITISH TRENCHES OF RATS 

Phosgene was not used alone, but had to be 
mixed with chlorine, and the deadly combina- 
tion of the two destroyed all life for miles be- 
hind the trenches. However, the British were 
ready for it. They had been drilled to put on 
their masks in a few seconds' time, on the first 
warning of a gas attack. When the clouds of 
chlorine and phosgene came over No Man's 
Land, they were prepared, and, except for cas- 
ualties among men whose masks proved defec- 
tive, the soldiers in the trenches came through 
with very few losses. All animal life, however, 
w T as destroyed. This was a blessing to the Brit- 
ish Tommy, whose trenches had been overrun 
with rats. The British had tried every known 
method to get rid of these pests, and now, thanks 
to the Germans, their quarters were most effec- 
tively fumigated with phosgene and every rat 
was killed. If only the "cooties" could have 
been destroyed in the same way, the Germans 
might have been forgiven many of their offenses. 

The disadvantages in the use of gas clouds 



THE BATTLE OF THE CHEMISTS 95 

became increasingly apparent. What was 
wanted was some method of placing the gas 
among the opponents in concentrated form, 
without wasting any of it on its way across from 
one line to the other. This led to the use of 
shell filled with materials which would produce 
gas. There were many advantages in these 
shell. They could be thrown exactly where it 
was desired that they should fall, without the 
help of the fickle winds. When the shell landed 
and burst, the full effect of its contents was 
expended upon the enemy. A gas cloud would 
rise over a wood, but with shell the wood could 
be filled with gas, which, once there, would lurk 
among the trees for days. Chemicals could be 
used in shell which could not be used in a cloud 
attack. The shell could be filled with a liquid, 
or even with a solid, because when it burst the 
filling would be minutely pulverized. And so 
German chemists were set to work devising all 
sorts of fiendish schemes for poisoning, chok- 
ing, or merely annoying their opponents. 

GAS THAT MADE ONE WEEP 

One of the novel shell the Germans used was 
known as the " tear-gas" shell. This was filled 



96 INVENTIONS OF THE GEEAT WAR 

with a liquid, tjae vapor of which was very irri- 
tating to the eyes. The liquid vaporized very 
slowly and so its effect would last a long time. 
However, the vapor did not permanently injure 
the eyes ; it merely filled them with tears to such 
an extent that a soldier was unable to see and 
consequently was confused and retarded in his 
work. The " tear-gas' ' shell were marked with 
a "T" by the Germans and were known as 
"T-shell." 

Another type of shell, known as the 
"K-shell," contained a very poisonous liquid, 
the object of which was to destroy the enemy 
quickly. The effect of this shell was felt at 
once, but it left no slow vapors on the ground, 
and so it could be followed up almost immedi- 
ately by an attack. Later on, the Germans de- 
veloped three types of gas shell — one known as 
the " Green Cross/' another as the "Yellow 
Cross," and the third as the "Blue Cross." 
The Green Cross shell was filled with diphos- 
gene, or a particularly dangerous combination 
of phosgene in liquid form, which would remain 
in pools on the ground or soak into the ground 
and would vaporize when it became warm. Its 
vapors were deadly. One had always to be on 



THE BATTLE OF THE CHEMISTS 97 

his guard against them. In the morning, when 
the sun warmed the earth and vapors were seen 
to rise from the damp soil, tests were made of 
the vapors to see whether it was mere water 
vapor or diphosgene, before men were allowed 
to walk through it. 

These vapors were heavier than air and would 
flow down into a trench, filling every nook and 
cranny. If phosgene entered a trench by a di- 
rect hit, the liquid would remain there for days, 
rendering that part of the trench uninhabitable 
except by men in gas-masks. The infected part 
of the trench, however, was cut off from the 
rest of the trench by means of gas-locks. In 
other words, blankets were used to keep the gas 
out, -and usually two blankets were hung so that 
a man in passing from one part of the trench 
to another could lift up the first blanket, pass 
under it, and close it carefully behind him be- 
fore opening the second blanket which led into 
the portion of the trench that was not infected. 

The Germans had all sorts of fiendish schemes 
for increasing the discomfort of the Allies. 
For instance, to some of their diphosgene shell 
they added a gas which caused intense vomit- 
ing. 



98 INVENTIONS OF THE GREAT WAR 

The Yellow Cross shell was another fiendish 
invention of the Huns. It was popularly known 
as "mustard gas" and was intended not to 
kill but merely to discomfort the enemy. The 
gas had a peculiar penetrating smell, some- 
thing like garlic, -and its fumes would burn the 
flesh wherever it was exposed to them, produc- 
ing great blisters and sores that were most 
distressing. The material in the shell was a 
liquid which was very hard to get rid of because 
it would vaporize so slowly. On account of the 
persistence of this vapor, lasting as it did for 
days, these gas shell were usually not fired 
by the Germans on lines that they expected to 
attack immediately. 

THE SNEEZING-SHELL 

The Blue Cross shell was comparatively 
harmless, although very annoying. It con- 
tained a solid which was atomized by the ex- 
plosion of the shell, and which, after it got 
into the nostrils, caused a violent sneezing. 
The material, however, was not poisonous and 
did not produce any casualties to speak of, 
although it was most unpleasant. A storm of 
Blue Cross shell could be followed almost im- 



THE BATTLE OF THE CHEMISTS 99 

mediately by an attack, because the effect of 
the shell would have been dissipated before 
the attackers reached the enemy who were still 
suffering from the irritation of their nostrils. 

GAS-MASKS 

As the different kinds of gas shell were de- 
veloped, the gas-masks were improved to meet 
them. In every attack there were "duds" or 
unexploded shell, which the chemists of the 
Allies analyzed. Also, they were constantly 
experimenting with new gases, themselves, 'and 
often could anticipate the Germans. The Allies 
were better able to protect themselves against 
gas attacks than the Germans, because 
there was a scarcity of rubber in Germany 
for the manufacture of masks. When it was 
found that phosgene was going to be used, the 
simple cotton-wad masks had to give way to 
more elaborate affairs with chemicals that 
would neutralize this deadly gas. And later 
when the mustard gas was used which attacked 
the eyes, and the sneezing-gas that attacked the 
nose, it was found necessary to cover the face 
completely, particularly the eyes; and so hel- 
mets of rubber were constructed which were 



100 INVENTIONS OF THE GREAT WAR 

tightly fitted around the neck under the coat 
collar. The inhaled aid was purified by pas- 
sage through a box or can filled with chemicals 
and charcoal made of various materials, such as 
cocoanut shells, peach pits, horse-chestnuts, and 
the like. Because the Germans had no rubber 
to spare, they were obliged to use leather, which 
made their masks stiff and heavy. 

GLASS THAT WILL NOT SHATTEK 

One of the greatest difficulties that had to be 
contended with was the covering of the eyes. 
There was danger in the use of glass, because 
it was liable to be cracked or broken, letting in 
the deadly fumes and gassing the wearer. Ex- 
periments were made with celluloid and similar 
materials, but the finest gas-masks produced 
in the war were those made for our own soldiers, 
in which the goggles were of glass, built up in 
layers, with a celluloid-like material between, 
which makes a tough composition that will 
stand up against a very hard blow. Even if 
it cracks, this glass will not shatter. 

The glasses were apt to become coated on 
the inside with moisture coming from the per- 
spiration of the face, and some means had to be 



THE BATTLE OF THE CHEMISTS 101 

provided for wiping them off. The French hit 
upon a clever scheme of having the inhaled air 
strike the glasses in a jet which would dry off 
the moisture and keep the glasses clear. Be- 
fore this was done, the masks were provided 
with little sponges on the end of a finger-piece, 
with which the glasses could be wiped dry with- 
out taking the masks off. 

But all this time, the Allies were not merely 
standing on the defensive. No sooner had the 
Germans launched their first attack than the 
British and French chemists began to pay back 
the Hun in kind. More attention was paid to 
the shell than the cloud attack, and soon gas 
shell began to rain upon the Germans. Not 
only were the German shell copied, but new 
gases were tried. Gas shell were manufac- 
tured in immense quantities. 

Then America took a hand in the war and 
our chemists added their help, while our fac- 
tories turned out steady streams of shell. If 
Germany wanted gas warfare, the Allies were 
determined that she should have it. Our chem- 
ists were not afraid to be pitted against the 
German chemists and the factories of the Allies 
were more than a match for those of the Cen- 



102 INVENTIONS OF THK GREAT WAR 

tral Powers. When the Germans first started 
the use of gas, apparently they counted only 
their own success, which they thought would 
be immediate and overwhelming. They soon 
learned that they must take what they gave. 
The Allies set them a pace that they could not 
keep up with. 

When the armistice brought the war to a 
sudden stop, the United States alone was mak- 
ing each day two tons of gas for every mile of 
the western front. If the war had continued, 
the Germans would have been simply deluged. 
As it was, they were getting far more gas than 
they could possibly produce in their own fac- 
tories and they had plenty of reason to regret 
their rash disregard of their contract at The 
Hague Conference. One gas we were making 
was of the same order as mustard gas but far 
more volatile, and had we had a chance to use 
it against the Germans they would have found 
it very difficult to protect themselves against its 
penetrating fumes. 

BATTLING WITH LIQUID FIKE 

Somewhat associated with gas warfare was 
another form of offensive which was introduced 



THE BATTLE OF THE CHEMISTS 103 

with the purpose of breaking up the dead-lock 
of trench warfare. A man could protect him- 
self against gas by using a suitable mask and 
clothing, but what could he do against fire? 
It looked as if trench defenders would have to 
give up if attacked with fire, and so, early in the 
war, the Germans devised apparatus for shoot- 
ing forth streams of liquid fire, and the Allies 
were not slow to copy the idea. 

The apparatus was either fixed or portable, 
but it was not often that the fixed apparatus 
could be used to advantage, because at best the 
range of the flame-thrower was limited and in 
few places were the trenches near enough for 
flaming oil to be thrown across the intervening 
gap. For this reason portable apparatus was 
chiefly used, with which a man could send out a 
stream for from a hundred to a hundred and 
fifty feet. On his back he carried the oil-tank, 
in the upper part of which there was a charge 
of compressed air. A pipe led from the tank 
to a nozzle which the man held in his hand, 
using it to direct the spray. 

There was some danger to the operator in 
handling a highly inflammable oil. The blaze 
might flare back and burn him, particularly 



104 INVENTIONS OF THE GREAT WAR 

when he was lighting the stream, and so a 
special way of setting fire to the spray had to be 
devised. Of course, the value of the apparatus 
lay in its power to shoot the stream as far as 
possible. The compressed air would sent the 
stream to a good distance, but after lighting, 
the oil might be consumed before it reached the 
desired range. Some way had to be found of 
igniting the oil stream far from the nozzle or 
as near the limit of its range as possible. And 
so two nozzles were used, one with a small open- 
ing so that it would send out a fine jet of long 
range, while the main stream of oil issued from 
the second nozzle. The first nozzle was mov- 
able with respect to the second and the two 
streams could be regulated to come together at 
any desired distance from the operator within 
the range of the apparatus. The fine stream 
was ignited and carried the flame out to the 
main stream, setting fire to it near the limit of 
its range. In this way a flare-back was avoided 
and the oil blazed where the flame was needed. 
The same sort of double nozzle was used on the 
stationary apparatus and, because weight was 
not a consideration, heavier apparatus was used 
which shot the stream to a greater distance. 



THE BATTLE OF THE CHEMISTS 105 

But flame-throwing apparatus had its draw- 
backs: there was always the danger that the 
tank of highly inflammable oil might be burst 
open by a shell or hand-grenade and its con- 
tents set on fire. The fixed apparatus was 
buried under bags of sand, but the man who 
carried flame-throwing apparatus on his back 
had to take his chances, not knowing at what 
instant the oil he carried might be set ablaze, 
turning him into a living, writhing, human 
torch. Because of this hazard, liquid fire did 
not play a very important part in trench war- 
fare; to set fire to the spray at its source with 
a well directed hand-grenade was too easy. 



There were certain situations, however, in 
which liquid fire played a very important part. 
After a line of trenches had been captured it 
was difficult to clear out the enemy who lurked 
in dugouts and underground passages. They 
would not surrender, and from their hidden 
recesses they could pour out a deadly machine- 
gun fire. The only way of dislodging them 
was to use the "fire broom." In other words, 
a stream of liquid fire was poured into the dug- 



106 INVENTIONS OF THE GREAT WAR 

out, burning out the men trapped in it. If 
there were a second exit, they would come tum- 
bling out in a hurry. If not, they would be 
burned to death. After the first sweep of the 
1 1 broom,' ' if there were any survivors, there 
would not be any fight left in them, and they 
would be quick to surrender before being sub- 
jected to a second dose of fire. 



CHAPTER VI 
Tanks 

THERE is no race-horse that can keep up 
with an automobile, no deer that can out- 
run a locomotive. A bicyclist can soon tire out 
the hardiest of hounds. Why? Because ani- 
mals run on legs, while machines run on wheels. 

As wheels are so much more speedy than legs, 
it seems odd that we do not find this form of 
locomotion in nature. There are many animals 
that owe their very existence to the fact that 
they can run fast. Why hasn't nature put 
them on wheels so that when their enemy ap- 
pears they can roll away, sedately, instead of 
having to jerk their legs frantically back and 
forth at the rate of a hundred strokes a minute? 

But one thing we must not overlook. Our 
wheeled machines must have a special road 
prepared for them, either a macadam highway 
or a steel track. They are absolutely helpless 

107 



108 INVENTIONS OF THE GREAT WAR 

when they are obliged to travel over rough 
country. No wheeled vehicle can run through 
fields broken by ditches and swampy spots, or 
over ground obstructed with boulders and tree- 
stumps. 

But it is not always possible or practicable 
to build a road for the machines to travel upon, 
and it is necessary to have some sort of self- 
propelled vehicle that can travel over all kinds 
of ground. 

Some time ago a British inventor developed 
a machine with large wheels on which were 
mounted the equivalent of feet. As the wheels 
revolved, these feet would be planted firmly on 
the ground, one after the other, and the machine 
would proceed step by step. It could travel 
over comparatively rough ground, and could 
actually walk up a flight of stairs. We have a 
very curious walking-machine in this country. 
It is a big dredge provided with two broad 
feet and a "swivel chair.' ' The machine 
makes progress by alternately planting its feet 
on the ground, lifting itself up, chair and all, 
pushing itself forward, and sitting down again. 

Although many other types of walking-ma- 
chines have been patented, none of them has 



TANKS 109 

amounted to very much. Clearly, nature hope- 
lessly outclasses us in this form of propulsion. 

Years ago it occured to one ingenious man 
that if wheeled machines must have tracks or 
roads for their wheels to run on, they might be 
allowed to lay their own tracks. And so he 
arranged his track in the form of an endless 
chain of plates that ran around the wheels of 
his machine. The wheels merely rolled on this 
chain, and as they progressed, new links of the 
track were laid down before them and the links 
they had passed over were picked up behind 
them. A number of inventors worked on this 
idea, but one man in particular, Benjamin Holt, 
of Peoria, Illinois, brought the invention to a 
high state of perfection. He arranged a series 
of wheels along the chain track, each carrying 
a share of the load of the machine, and each 
mounted on springs so that it would yield to 
any unevenness of the ground, just as a cater- 
pillar conforms itself to the hills and dales of 
the surface it creeps over. In fact, the ma- 
chine was called a "caterpillar" tractor be- 
cause of its crawling locomotion. 

But it was no worm of a machine. In power 
it was a very elephant. It could haul loads 



110 INVENTIONS OF THE GREAT WAR 

that would tax the strength of scores of horses. 
Stumps and boulders were no obstacles in its 
path. Even ditches could not bar its progress. 
The machine would waddle down one bank 
and up the other without the slightest diffi- 
culty. It was easily steered; in fact, it could 
turn around in its own length by traveling for- 
ward on one of its chains, or traction-belts, 
and backward on the other. The machine was 
particularly adapted to travel on soft or plowed 
ground, because the broad traction-belts gave 
it a very wide bearing and spread its weight 
over a large surface. It was set to work on 
large farms, hauling gangs of plows and culti- 
vators. Little did Mr. Holt think, as he 
watched his powerful mechanical elephants at 
work on the vast Western wheat-fields, that 
they, or rather their offspring, would some day 
play a leading role in a war that would rack the 
whole world. 

But we are getting ahead of our story. To 
start at the very beginning, we must go back 
to the time when the first savage warrior used 
a plank of wood to protect himself from the 
rocks hurled by his enemy. This was the start 



TANKS 111 

of the never-ending competition between arms 
and armor. As the weapons of offense de- 
veloped from stone to spear, to arrow, to arque- 
bus, the wooden plank developed into a shield 
of brass and then of steel; and then, since a 
separate shield became too bothersome to 
carry, it was converted into armor that the 
warrior could wear and so have both hands free 
for battle. For every improvement in arms 
there was a corresponding improvement in 
armor. 

After gunpowder was invented, the idea 1 of 
armor for men began to wane, because no armor 
could be built strong enough to ward off the 
rifle-bullet and at the same time light enough 
for a man to wear. The struggle between arms 
and armor was then confined to the big guns 
and the steel protection of forts and war-ships. 

But not so long ago the machine-gun was in- 
vented, and this introduced a new phase of war- 
fare. Not more than one rifle-bullet in a thou- 
sand finds its mark on the battle-field. The 
Boers in the battle of Colenso established a 
record with one hit in six hundred shots. In 
the excitement of battle men are too nervous to 
take careful aim and they are apt to fire either 



112 INVENTIONS OF THE GREAT WAR 

too high or too low, so that the mortality is 
not nearly so great as some would expect. But 
with the machine-gun there is not this waste of 
ammunition, because it fires a stream of 
bullets, the effect of which can readily be deter- 
mined by the man who operates the volley. The 
difference between the machine-gun fire and 
rifle fire is something like the difference between 
hitting a tin can with a stone or with a stream of 
water. It is no easy matter to score a hit with 
the stone ; but any one can train a garden hose 
on the can, because he can see where the water is 
striking and move his hose accordingly until he 
covers the desired spot. In the -same way, 
with the machine-gun, it is much, easier to train 
the stream of bullets upon the mark, and, having 
once found the mark, to hold the aim. That is 
one reason why the destruction of a machine- 
gun is so tremendous ; another, of course, being 
that it will discharge so many more shots per 
minute than the common rifle. 

In the Eusso-Japanese War, the Eussians 
played havoc with the attacking Japanese at 
Port Arthur by using carefully concealed ma- 
chine-guns, and the German military attaches 
were quick to note the value of the machine- 




(C) Underwood & Underwood 

Even Trees were no Barrier to the British Tank 




Press Illustrating Service 

The German Tank was very heavy and cumbersome 



TANKS 113 

gun. Secretely they manufactured large num- 
bers of machine-guns and established a special 
branch of service to handle the guns, and they 
developed the science of using them with telling 
effect. And so, when the recent great war sud- 
denly broke out, they surprised the world with 
the countless number of machine-guns they pos- 
sessed and the efficient use to which they put 
them. Thousands of British soldiers in the 
early days of the war fell victims to these death- 
dealing machines. Two or three men with a 
machine-gun could defy several companies of 
soldiers, especially when the attackers had to 
cut their way through barbed-wire entangle- 
ments. It was clearly evident that something 
must be done to defend the men against the 
machine-gun; for to charge against it meant, 
simply, wholesale slaughter. 

At first the only means of combating the ma- 
chine-guns seemed to be to destroy them with 
shell-fire; but they were carefully concealed, 
and it was difficult to search them out. Only 
by long-continued bombardment was it possible 
to destroy them and tear away the barbed wire 
sufficiently to permit of a charge. Before an 
enemy position was stormed it was subjected to 



114 INV^JNTIDNB OF THE GBEAT WAB 

the fire of thousands of guns of all calibers for 
hours and even days. 

But this resulted in notifying the enemy that 
a charge was ere long to be attempted at a 
certain place, and he could assemble his reserves 
for a counter-attack. Furthermore, the Ger- 
mans learned to conceal their machine-guns in 
dugouts twenty or thirty feet underground, 
where they were safe from the fire of the big 
guns, and then, when the fire let up, the weapons 
would be dragged up to the surface in time to 
mow down the approaching infantry. 

It was very clear that something would have 
to be done to combat the machine-gun. If the 
necessary armor was too heavy for the men 
to carry, it must carry itself. Armored auto- 
mobiles were of no service at all, because they 
could not possibly travel over the shell-pitted 
ground of No Man's Land. The Eussians 
tried a big steel shield mounted on wheels, 
which a squad of soldiers would push ahead 
of them, but their plan failed because the wheels 
would get stuck in shell-holes. A one-man 
shield on wheels was tried by the British. Un- 
der its shelter a man could steal up to the barbed 
wire and cut it and even crawl up to a machine- 



TANKS 115 

gun emplacement and destroy it with a hand- 
grenade. But this did not prove very success- 
ful, either, because the wheels did not take 
kindly to the rough ground of the battle-field. 

And here is where we come back to Mr. 
Holt's mechanical elephants. Just before the 
great war broke out, Belgium — poor unsus- 
pecting Belgium — was holding an agricultural 
exhibit. An American tractor was on exhi- 
bition. It was the one developed by Mr. 
Holt, and its remarkable performances gained 
for it a reputation that spread far and 
wide. Colonel E. D. Swinton of the British 
Army heard of the peculiar machine, and im- 
mediately realized the advantages of an ar- 
mored tractor for battle over torn ground. 
But in the first few months of the war that 
ensued, this idea was forgotten, until the ef- 
fectiveness of the machine-gun and the neces- 
sity for overcoming' it recalled the matter 
to his mind. At his suggestion a caterpillar 
tractor was procured, and the military engi- 
neers set themselves to the task of designing an 
armored body to ride on the caterpillar-trac- 
tor belts. Of course the machine had to be 



116 INVENTIONS OF THE GREAT WAR 

entirely re-designed. The tractor was built for 
hauling loads, and not to climb out of deep shell- 
holes; but by running the traction-belts over 
the entire body of the car, and running the 
forward part of the tractor up at a sharp an- 
gle the engineers overcame that difficulty. 

In war, absolute secrecy is essential to the 
success of any invention, and the British en- 
gineers were determined to let no inkling of 
the new armored automobiles reach the enemy. 
Different parts of the machines were made in 
different factories, so that no one would have 
an idea of what the whole would look like. At, 
first the new machine was known as a " land- 
cruiser' ' or "land-ship"; but it was feared that 
this very name would give a clue to spies, and 
so any descriptive name was forbidden. Many 
of the parts consisted of rolled steel plates 
which might readily be used in building up ves- 
sels to hold water or gasolene ; and to give the 
impression that such vessels were being con- 
structed the name "tank" was adopted. The 
necessity of guarding even the name of the ma- 
chines was shown later, when rumors leaked 
out that the tanks were being built to carry 
water over the desert regions of Mesopotamia 



TANKS 117 

and Egypt. Another curious rumor was that 
the machines were snow-plows for use in Eus- 
sia. To give some semblance of truth to this 
story, the parts were carefully labeled, "For 
Petrograd." 

Probably never was a military secret so well 
guarded as this one, and when, on September 
15, 1916, the waddling steel tractors loomed up 
out of the morning mists, the German fighters 
were taken completely by surprise. Two days 
before, their airmen had noticed some peculiar 
machines which they supposed were armored 
automobiles. They had no idea, however, that 
such formidable monsters were about to de- 
scend upon them. 

The tanks proceeded leisurely over the shell- 
torn regions of No Man's Land, wallowing 
down into shell-holes and clambering up out of 
them with perfect ease. They straddled the 
trenches and paused to pour down them streams 
of machine-gun bullets. Wire entanglements 
were nothing to them; under their weight steel 
wire snapped like thread. The big brutes 
marched up and down the lines of wire, treading 
them down into the ground and clearing the way 
for the infantry. Even trees were no barrier 



118 INVENTIONS OF THE GREAT WAR 

to these tanks. Of course they did not attack 
large ones, but the smallish trees were simply 
broken down before their onslaughts. As for 
concrete emplacements for machine-guns, the 
tanks merely rode over them and crushed them. 
Those who attempted to defend themselves in 
the ruins of buildings found that the tanks 
could plow right through walls and bring them 
down in a shower of bricks and stone. There 
was no stopping these monsters, and the Ger- 
mans fled in consternation before them. 

There were two sizes of tanks. The larger 
ones aimed to destroy the machine-gun emplace- 
ments, and they were fitted up with guns for fir- 
ing a shell. The smaller tanks, armed with 
machine-guns, devoted themselves to fighting 
the infantry. British soldiers following in the 
wake of the bullet-proof tank were protected 
from the shots of the enemy and were ready to 
attack him with bayonets when the time was 
ripe. But the tanks also furnished an indirect 
protection for the troops. It was not necessary 
for the men to conceal themselves behind the 
big tractors. Naturally, every Hun who stood 
his ground and fought, directed all his fire upon 
the tanks, leaving the British infantry free to 



M 



TANKS 119 

charge virtually unmolested. The success of 
the tank was most pronounced. 

In the meantime the French had been in- 
formed of the plans of their allies, and they set 
to work on a different design of tractor. It 
was not until six months later that their ma- 
chines saw service. The French design dif- 
fered from the British mainly in having the 
tractor belt confined to the wheels instead of 
running over the entire body of the tank. It 
was more blunt than the British and was pro- 
vided at the forward end with a steel cutting- 
edge, which adapted it to break its way through 
wire entanglements. At each end there are two 
up ward- turning skids which helped the tank 
to lift itself out of a hole. The larger machines 
carried a regular 75-millimeter (3-inch) field- 
gun, which is a very formidable weapon. They 
carried a crew of one officer and seven men. 

Life in a tank is far from pleasant. The heat 
and the noise of machinery and guns are terrific. 
Naturally, ventilation is poor and the fumes and 
gases that accumulate are most annoying, to 
say the least. Sometimes the men were over- 
come by them. But war is war, and such dis- 
comforts had to be endured, 



120 INVENTIONS OF THE GKEAT WAR 

But the tank possessed one serious defect 
which the Germans were not slow to discover. 
Its armor was proof against machine-gun fire, 
but it could not ward off the shells of field- 
guns, and it was such a slow traveler that the 
enemy did not find it a very difficult task to 
hit it with a rapid-fire gun if the gunner could 
see his target. And so the Germans ordered up 
their guns to the front lines, where they could 
score direct hits. Only light guns were used 
for this purpose, especially those whose rifling 
was worn down by long service, because 
long range was not necessary for tank 
fighting. 

When the Germans began their final great 
drive, it was rumored that they had built some 
monster tanks that were far more formidable 
than anything the Allies had produced. Un- 
like the British, they used the tanks not to lead 
the army but to follow and destroy small nests 
of French and British that were left behind. 
When the French finally did capture one of the 
German tanks, which had fallen into a quarry, 
it proved to be a poor imitation. It was an 
ugly-looking affair, very heavy and cumber- 
some. Owing to the scarcity of materials for 



TANKS 121 

producing high-grade armor, it had to make 
up in thickness of plating what it lacked in 
quality of steel. The tank was intended to 
carry a crew of eighteen men and it fairly 
bristled with guns, but it could not manoeuver 
as well as the British tank; for when some 
weeks later a fleet of German tanks encountered 
a fleet of heavy British tanks, the Hun machines 
were completely routed. 

It was then that the British sprang another 
surprise upon the Germans. After the big 
fellows had done their work, a lot of baby tanks 
appeared on the scene and chased the German 
infantry. These little tanks could travel at a 
speed of twelve miles an hour, which is about 
as fast as an ordinary man can run. " Whip- 
pets/ ' the British called them, because they 
were like the speedy little dogs of that name. 
They carried but two men, one to guide the tank 
and the other to operate the machine-gun. The 
French, too, built a light "mosquito" tank, 
which was even smaller than the British tank, 
and fully as fast. It was with these machines, 
which could dart about quickly on the battle- 
field and dodge the shell of the field-guns, and 
which were immune to the fire of the machine- 



122 INVENTIONS OF THE GREAT WAR 

gun, that the Allies were able to make progress 
against the Germans. 

When the Germans retired, they left behind 
them nests of machine-guns to cover the with- 
drawal of their armies. These gunners were 
ordered to fight to the very end. They looked 
for no mercy and expected no help. Had it 
not been for the light tanks, it would have been 
well nigh impossible to overcome these deter- 
mined bodies of men without frightful losses. 

Since America invented the machine-gun and 
also barbed wire, and since America furnished 
the inspiration for the tank with which to tram- 
ple down the wire entanglements and stamp out 
the machine-guns, naturally people expected 
our army to come out with something better 
than anything produced by our allies. We did 
turn out a number of heavy machines patterned 
after the original British tank, with armor that 
could stand up against heavy fire, and we also 
produced a small and very speedy tank similar 
to the French "baby" tank, but before we could 
put these into service the war ended. The 
tanks we did use so effectively at St.-Mihiel 
and in the Argonne Forest were supplied by 
the French. 



CHAPTER VIX 

The War in the Air 

WE Americans are a peace-loving people, 
which is the very reason why we went 
into the war. We had to help down the 
power that was disturbing the peace of the 
world. We do not believe in conquests — at 
least of the type that Germany tried to force 
— and yet there are certain conquests that we 
do indulge in once in a while. 

Eleven years before Germany undertook to 
conquer Europe two young Americans made the 
greatest conquest that the world has ever seen. 
The Wright brothers sailed up into the heavens 
and gained the mastery of the air. They of- 
fered their conquest to the United States; but 
while we accepted their offering with enthusi- 
asm at first, we did not know what to do with 
the new realm after we got it. There seemed 
to be no particular use in flying. It was just 

123 



124 INVENTIONS OF THE GBEAT WAR 

a bit too risky to be pleasant sport, and about 
all we could see in it was an exhibition for the 
circus or the county fair. 

Not so in Europe, however. Flying meant 
something over there — there where the fron- 
tiers have ever bristled with big guns and 
strong fortifications, and where huge military 
forces have slept on their arms, never knowing 
what dreadful war the morning would bring 
forth. The war-lovers hailed the airplane as 
a new instrument with which to terrorize their 
neighbors; the peace-lovers saw in it another 
menace to their homes ; it gave them a new fron- 
tier to defend. And so the military powers of 
Europe took up the airplane seriously and 
earnestly and developed it. 

At first military authorities had rated the 
airplane chiefly as a flying scout. Some bomb- 
dropping experiments had been made with it, 
but it proved very difficult to land the bombs 
near the target, and, besides, machines of those 
days were not built to carry very heavy loads, 
so that it did not seem especially profitable to 
attack the enemy from the skies. As for actual 
battles up among the clouds, they were dreamed 
of only by the writers of fiction. But wild 



THE WAR IN THE AIR 125 

dreams became stern realities in the mighty 
struggle between the great powers of the world. 

EYES IN THE SKY 

As a scouting-maehine the airplane did 
prove to be far superior to mounted patrols 
which used to perform scout-work. In fact, it 
changed completely the character of modern 
warfare. From his position high up in the 
heavens the flying scout had an unobstructed 
view of the country for miles and he could see 
just what the enemy was doing. He could see 
whether large forces of men were collecting for 
an attack. He could watch the course of sup- 
ply-trains, and judge of their size. He could 
locate the artillery of the enemy and come back 
with information which in former times a scout 
posted in a tall tree or even in a captive balloon 
could not begin to acquire. Surprise attacks 
were impossible, with eyes in the sky. The 
aviator could help his own batteries by signal- 
ing to them where to send their shell, and when 
the firing began he would spot the shots as they 
landed and signal back to the battery how to 
correct its aim so as to drop the shell squarely 
on the target. 



126 INVENTIONS OF THE GREAT WAR 

The French sprang a surprise on the Ger- 
mans by actually attacking the infantry from 
the sky. The idea of attack from overhead 
was so novel that armies did not realize the 
danger of exposing themselves behind the bat- 
tle-front. Long convoys of trucks and masses 
of infantry moved freely over the roads 
behind the lines and they were taken by sur- 
prise when the French began dropping steel 
darts upon them. These were about the size 
of a pencil, with pointed end and fluted tail, 
so that they would travel through the air like 
an arrow. The darts were dropped by the 
hundred wherever the airmen saw a large 
group of the enemy, and they struck with suf- 
ficient velocity to pierce a man from head to 
foot. But steel darts were not used very long. 
The enemy took to cover and then the only way 
to attack him was to drop explosives which 
would blow up his shelter. 

At the outset, air scouts were more afraid of 
the enemy on the ground than in the sky. The 
Germans had anti-aircraft guns that were fired 
with accuracy and accounted for many Allied 
planes. In those days, airplanes flew at com- 
paratively low altitudes and they were well 



THE WAR IN THE All 12? 

within the reach of the enemy's guns. But it 
was not long before the airplanes began to fight 
one another. Each side was very much an- 
noyed by the flying scouts of its opponents and 
after a number of pistol duels in the sky the 
French began to arm their planes with machine- 
guns. 

Two months after the war started the first 
airplane was sent crashing to earth after a bat- 
tle in the sky. The fight took place five thou- 
sand feet above the earth, between a French 
and a German machine. The German pilot was 
killed and the plane fell behind the French 
lines, carrying with it a Prussian nobleman 
who died before he could be pulled out of the 
wreckage. The war had been carried into the 
skies. But if scouts were to fight one another, 
they could not pay much attention to scouting 
and spotting and it began to be realized that 
there were four distinct classes of work for the 
airplane to do — scouting, artillery spotting, bat- 
tling, and bombing. Each called for special 
training and its own type of machine. As air 
fighting grew more specialized these classes 
were further subdivided, but we need not go into 
such refinements. 



128 INVENTIONS OF THE GREAT WAR 

AIR SCOUTS AND THEIR DANGERS 

The scouting-airplane usually carried two 
men, one- to drive the machine and the other to 
make observations. The observer had to carry 
a camera, to take photographs of what lay be- 
low, and he was usually equipped with a wire- 
less outfit, with which he could send important 
information back to his own base. The camera 
was sometimes fitted with a stock like that of 
a gun, so that it could be aimed from the 
shoulder. Some small cameras were shaped so 
that they could be held in the hand like a pistol 
and aimed over the side of the fuselage, or body, 
of the airplane ; but the best work was done with 
large cameras fitted with telescopic lenses, or 
"telephoto" lenses, as they are called. Some 
of these were built into the airplane, with the 
lens opening down through the bottom of the 
fuselage. 

The scouting-airplane carried a machine-gun, 
not for attack, but for defense. It had to be a 
quick climber and a good dodger, so that it 
could escape from an attacking plane. Usually 
it did not have to go very far into the enemy 
country, and it was provided with a large wing- 



20miies 
perbour 



60 miles 
per hour 



100 miles 
per hour 



- 
•K 



EH 







i 



How an object dropped from the Woolworth Building would 
increase its speed in falling 



THE WAR IN THE AIR 129 

spread, so that if anything happened to the 
engine, it could volplane, or glide back, to its 
own lines. As the scouting-planes were large, 
they offered a big target to anti-aircraft guns, 
and so the work of the air scout was to swoop 
down upon the enemy, when, of course, the 
machine would be traveling at high velocity, 
because it would have all the speed of falling 
added to that which its own propeller gave it. 

It was really a very difficult matter to hit a 
rapidly moving airplane; and even if it were 
hit, there were few spots in which it could be 
mortally wounded. Hundreds of shots could go 
through the wings of an airplane without im- 
pairing its flying in the least. The engine, too, 
could be pretty well peppered with ordinary 
bullets without being disabled. As for 'the men 
in the machine, they furnished small targets, 
and even they could be hit in many places with- 
out being put entirely out of business. And so 
the dangers of air scouting were not so great 
as might at first be supposed. 

One of the most vulnerable spots in the air- 
plane was the gasolene tank. If that w T ere 
punctured so that the fuel would run out, the 
airplane would have to come to the ground. 



130 INVENTIONS OF THE GREAT WAR 

Worse still, the gas-olene might take fire and 
there was nothing the aviator dreaded more 
than fire. There were occasions in which he had 
to choose between leaping to earth and burn- 
ing to death, and the former was usually pre- 
ferred as a quicker and less painful death. 
In some of the later machines the gasolene-tank 
could be pitched overboard if it took fire, by the 
throwing of a lever, and then the aviator could 
glide to earth in safety. 

THE SELF-HEALING GASOLENE-TANK 

One of the contributions which we made to 
military aeronautics was a gasolene-tank that 
was puncture-proof. It was made of soft rub- 
ber with a thin lining of copper. There are 
some very soft erasers on the market through 
which you can pass a lead pencil and never find 
the hole after it has passed through, because 
the rubber has closed in and healed the wound. 
Such was the rubber used in the gasolene-tank. 
It could be peppered with bullets and yet would 
not leak a drop of gasolene, unless the bullet 
chanced to plow along the edge of the tank 
and open a long gash. 

The Germans used four different kinds of 



THE WAR IN THE AIR 131 

cartridges in their aircraft guns. The first 
carried the ordinary bullet, a second type had 
for its bullet a shell of German silver filled with 
a phosphor compound. This was automatically 
ignited through a small opening in the base of 
the shell when it w T as fired from the gun and it 
left a trail of smoke by which the gunner could 
trace its course through the air and correct his 
aim. At night the bright spot of light made 
by the burning compound would serve the same 
purpose. Such a bullet, if it hit an ordinary 
gasolene-tank, would set fire to its contents. 
The bullet would plow through the tank and out 
at the opposite side and there, at its point of 
exit, is where the gasolene would be set on 
fire. Such incendiary bullets were repeatedly 
fired into or through the rubber tanks and the 
hole would close behind the bullet, preventing 
the contents from taking fire. The two other 
types of bullets referred to were an explosive 
bullet or tiny shell which would explode on 
striking -the target and a perforating steel bul- 
let which was intended to pierce armor or pene- 
trate into vital parts of an airplane engine. 

Machines with which artillery-spotting was 
done were usually manned by a pilot and an ob- 



132 INVENTIONS OF THE GREAT WAR 

server, so that the latter could devote his entire 
attention to noting the fire of the guns and 
signaling ranges without being hampered by 
having to drive the machine. These machines 
were usually of the pusher type," so that the ob- 
server could have an unobstructed view. They 
did not have to be fast machines. It was really 
better for them to move slowly. Had it been 
possible for them to stop altogether and hover 
over the spot that was being shelled, it would 
have been a distinct advantage. That would 
have given the observer a chance to note with 
better accuracy the fall of the shell. Like the 
scout, the spotter had to be a fast climber, so 
that it could get out of the range of enemy guns 
and run away from attacking planes. 

GIANTS OF THE SKY 

The largest war-planes were the bomb-drop- 
ping machines. They had to be capable of 
carrying heavy loads of explosives. They were 
usually slow machines, speed being sacrificed 
in carrying-capacity. 

The Germans paid a great deal of attention 
to big bomb-dropping machines, particularly 
after their Zeppelins proved a failure. Their 



THE WAR IN THE Affi 133 

huge G-othas were built to make night raids on 
undefended cities. The Italians and the British 
retaliated with machines that were even larger. 
At first the French were inclined to let giant 
planes alone. They did not care to conduct 
long-distance bombing-raids on German cities 
because their own important cities were so near 
the battle-front that the Germans could have 
done those places more harm than the French 
could have inflicted. Later they built some 
giant machines, although not so large as those 
of the Italians and the British. 

The large triplane Capronis built by the 
Italians held a crew of three men. They were 
armed with three guns and carried 2750 pounds 
of explosives. That made a useful load of 4000 
pounds. The machine was driven by three en- 
gines with a total of 900 horse-power. 

The big British plane was the Handley-Page, 
which had a wing-spread of 125 feet and could 
carry a useful load of three tons. These enor- 
mous machines conducted their raids at night 
because they were comparatively slow and could 
not defend themselves against speedy battle- 
planes. The big Italian machines used ' * search- 
light " bombs to help them locate important 



134 INVENTIONS OF THE GREAT WAR 

points on the ground beneath. These were 
brilliant magnesium torches suspended from 
parachutes so that they would fall slowly and 
give a broad illumination, while the airplane it- 
self was shielded from the light by the para- 
chute. 

But these giants were not the only bombing- 
machines. There were smaller machines that 
operated over the enemy's battle-line and 
dropped bombs on any suspicious object behind 
the enemy lines. These machines h?d to be con- 
voyed by fast battle-planes which fought off 
hostile airmen. 

HOW FAST IS A HUNDRED AND FIFTY MILES 
PER HOUR? 

In naval warfare the battle-ship is the big- 
gest and heaviest ship of the fleet, but in the 
air the battle-planes are the lightest and the 
smallest of the lot. They are one-man ma- 
chines, as a rule, little fellows, but enormously 
speedy. Speed is such an important factor in 
aerial warfare that there was a continuous 
struggle between the opposing forces to pro- 
duce the faster machine. Airplanes were con- 
stantly growing speedier, until a speed of 150 



THE WAR IN THE AIR 135 

miles per hour was not an uncommon rate of 
travel. It is hard to imagine such a speed as 
that, but we may gain some idea if we consider 
a falling object. The observation platform of 
the Woolworth Building, in New York, is about 
750 feet above the ground. If you should drop 
an object from this platform you would start 
it on a journey that would grow increasingly 
speedy, particularly as it neared the ground. 
By the time it had dropped from the sixtieth 
story to the fifty-ninth it would have attained a 
speed of nearly 20 miles per hour. (We are not 
making any allowances for the resistance of the 
air and what it would do to check the speed.) As 
it passed the fiftieth story it would be traveling 
as fast as an express-train, or 60 miles per hour. 
It would finally reach the ground with a speed 
equal to that of a fast battle-plane — 150 miles 
per hour. 

The battle-plane was usually fitted with a 
single machine-gun that was fixed to the air- 
plane, so that it w r as brought to bear on the 
target by aiming the entire machine. In this the 
plane was something like a submarine, which 
must point its bow at its intended victim in or- 
der to aim its torpedo. The operator of the bat- 



136 INVENTIONS OF THE GREAT WAR 

tie-plane simply drove his machine at the enemy 
and touched a button on his steering-lever to 
start his machine-gun going. 

SHOOTING THROUGH THE PROPELLER 

Now, the fleetest machines and the most easily 
manceuvered are those of the tractor type, that 
is, the ones which have the propeller in front; 
but having the propeller in front is a handicap 
for a single-seater machine, for the gun has to 
be fired through the propeller and the bullets 
are sure to hit the propeller-blades. Neverthe- 
less the French did fire right through the pro- 
peller, regardless of whether or not the blades 
were hit; but at the point where they came in 
line with the fire of the gun they were armored 
with steel, so that there was no danger of their 
being cut by the bullets. It was calculated that 
not more than one bullet in eighteen would strike 
the propeller-blade and be deflected from its 
course, which was a very trifling loss ; neverthe- 
less, it was a loss, and on this account a mechan- 
ism was devised which would time the opera- 
tions of the machine-gun so that the shots would 
come only when the propeller-blades were clear 
of the line of fire. 




Machine Gun mounted to Fire over the Blades of the Propeller 









s iJ auj Bli!!: 





£ 



, ^m^^^^'^ : ^<'M^M^ -^ai$ m 






— \* 



Courtesy of "Scientific American " 

Mechanism for Firing Between the Blades of the Propeller 

The cam B on the propeller shaft lifts the rod C, rocking the angle 
lever D which moves the rod E and operates the firing-piece F. 
Firing may be stopped by means of lever Hand Bowden wire G. 
I is the ejection-tube for empty cartridges. 



THE WAR IN THE AIR 137 

A cam placed on the propeller-shaft worked 
the trigger of the machine-gun. This did not 
slow up the fire of the machine-gun. Quite the 
contrary. We are apt to think of the fire of the 
machine-guns as very rapid, but they usually 
fire only about five hundred rounds per minute, 
while an airplane propeller will make something 
like twelve hundred revolutions per minute. 
And so the mechanism was arranged to pull the 
trigger only once for every two revolutions of 
the propeller. 

FIGHTING AMONG THE CLOUDS 

There was no service of the war that began to 
compare with that of the sky fighter. He had 
to climb to enormous heights. Air battles took 
place at elevations of twenty thousand feet. 
The higher the battle-plane could climb, the bet- 
ter, because the man above had a tremendous 
advantage. Clouds were both a haven and a 
menace to him. At any moment an enemy plane 
might burst out of the clouds upon him. He 
had to be ready to go through all the thrilling 
tricks of a circus performer so as to dodge the 
other fellow and get a commanding position. 
If he were getting the worst of it, he might 



138 INVENTIONS OF THE" GREAT WAR 

feign death and let his machine go tumbling and 
fluttering down for a thousand feet or so, only 
to recover his equilibrium suddenly and dart 
away when the enemy was thrown off his guard. 
He might escape into some friendly cloud, but 
he dared not hide in it very long, lest he get 
lost. 

It is a peculiar sensation that comes over an 
aviator when he is flying through a thick mass 
of clouds. He is cut off from the rest of the 
world. He can hear nothing but the terrific 
roar of his own motor and the hurricane rush 
of the wind against his ears. He can see 
nothing but the bluish fog of the clouds. He 
begins to lose all sense of direction. His com- 
pass appears to swing violently to and fro, when 
really it is his machine that is zig-zagging under 
his unsteady guidance. The more he tries to 
steady it, the worse becomes the swing of the 
compass. As he turns he banks his machine 
automatically, just as a bicyclist does when 
rounding a corner. He does this unconsciously, 
and he may get to spinning round and round, 
with his machine standing on its side. In some 
cases aviators actually emerged from the clouds 
with their machines upside down. To be sure, 



THE WAR IN THE AIR 139 

this was not an alarming position for an expe- 
rienced aviator ; at the same time, it was not al- 
together a safe one. A machine was some- 
times broken by its operator's effort to right it 
suddenly. And so while the clouds made handy 
shelters, they were not always safe harbors. 

To the battle-plane fell the task of clearing 
the air of the enemy. If the enemy's battle- 
planes were disposed of, his bombing-planes, 
his spotters, and his scouts could not operate, 
and he would be blind. And so each side tried 
to beat out the other with speedier, more power- 
ful, and more numerous battle-planes. Fast 
double-seaters were built with guns mounted so 
that they could turn in any direction. 

THE FLYING TANK 

The Germans actually built an armored bat- 
tle-plane known as the flying tank. It was a 
two-seater intended mainly for attacking in- 
fantry and was provided with two machine- 
guns that pointed down through the floor of the 
fuselage. A third gun mounted on a revolving 
wooden ring could be used to fight off hostile 
planes. The bottom and sides of the fuselage 
or body of the airplane from the gunner's cock- 



140 INVENTIONS OF THE GREAT WAR 

pit forward were sheathed with plates of steel 
armor. The machine was a rather cumbersome 
craft and did not prove very successful. A fly- 
ing tank was brought down within the American 
lines just before the signing of the armistice. 

amekica's help 

Our own contribution to the war in the air 
was considerable, but we had hardly started be- 
fore the armistice brought the righting to an 
end. Before we entered the war we did not 
give the airplane any very serious considera- 
tion. To be sure, we built a large number of 
airplanes for the British, but they were not 
good enough to be sent to the front ; they were 
used merely as practice planes in the British 
training-schools. We knew that we were hope- 
lessly outclassed, but we did not care very 
much. Then we stepped into the conflict. 

"What can we do to help?" we asked our 
allies, and their answer gave us a shock. 

"Airplanes!" they cried. "Build us air- 
planes — thousands of them — so that we can 
drive the enemy out of the air and blind his 
armies ! ' 9 

It took us a while to recover from our sur- 



THE WAR IN THE AIR 141 

prise, and then we realized why we had been 
asked to build airplanes. The reputation of the 
United States as a manufacturer of machinery 
had spread throughout the world. We Ameri- 
cans love to take hold of a machine and turn it 
out in big quantities. Our allies were sure that 
we could turn out first-class airplanes, and many 
of them, if we tried. 

Congress made an appropriation of six hun- 
dred and forty million dollars for aeronautics, 
and then things began to hum. 

A BIRTHDAY PRESENT TO THE NATION 

The heart of an airplane is its engine. We 
know a great deal about gasolene-engines, es- 
pecially automobile engines ; but an airplane en- 
gine is a very different thing. It must be tre- 
mendously powerful, and at the same time ex- 
tremely light. Every ounce of unnecessary 
weight must be shaved off. It must be built 
with the precision of a watch; its vital parts 
must be true x o a ten-thousandth part of an inch. 
It takes a very powerful horse to develop one 
horse-power for a considerable length of time. 
It would take a hundred horses to supply the 
power for even a small airplane, and they would 



142 INVENTIONS OF THE GREAT WAR 

weigh a hundred and twenty thousand pounds. 
An airplane motor of the same power would 
weigh less than three hundred pounds, which is 
a quarter of the weight of a single horse. It 
was this powerful, yet most delicate, machine 
that we were called upon to turn out by the thou- 
sand. There was no time to waste; a motor 
must be designed that could be built in the 
American way, without any tinkering or fussy 
hand-work. 

Two of our best engineers met in a hotel in 
Washington on June 3, 1917, and worked for 
five days without once leaving their rooms. 
They had before them all the airplane knowl- 
edge of our allies. American engine-builders 
offered up their trade secrets. Everything was 
done to make this motor worthy of America's 
reputation. There was a race to have the mo- 
tor finished by the Fourth of July. Sure 
enough, on Independence Day the finished motor 
was there in Washington — the "Liberty mo- 
tor," a birthday present to the nation. 

Of course that did not mean that we were 
ready at once to turn out Liberty motors by the 
thousand. The engine had to undergo many 
tests and a large number of alterations before it 



THE WAR IN THE AIR 143 

was perfectly satisfactory and then special ma- 
chinery had to be constructed before it could 
be manufactured in quantity. It was Thanks- 
giving Day before the first manufactured Lib- 
erty was turned out and even after that change 
upon change was made in this little detail and 
that. It was not until a year after we went to 
war that the engine began to be turned out in 
quantity. 

There was nothing startlingly new about the 
engine. It was a composite of a number of 
other engines, but it was designed to be turned 
out in enormous quantities, and it was remark- 
ably efficient. It weighed only 825 pounds and 
it developed over 420 horse-power. Some ma- 
chines went up as high as 485 horse-power. An 
airplane engine weighing less than 2 pounds per 
horse-power is wonderfully efficient. Of course 
the Liberty was too heavy for a light battle- 
plane (a heavy machine, no matter how power- 
ful, cannot make sharp turns), but it was ex- 
cellent for other types of airplanes and large 
orders for Liberty engines were made by our 
allies. Of course we made other engines as 
well, and the planes to carry them. We built 
large Caproni and Handley-Page machines, and 



144 INVENTIONS OF THE GREAT WAR 

we were developing some remarkably swift and 
powerful planes of our own when the Germans 
thought it about time to stop fighting. 

FLYING BOATS 

So far we have said nothing about the sea- 
planes which were used in large numbers to 
watch for submarines. These were big flying 
boats in which speed was not a very important 
matter. One of the really big machines we de- 
veloped, but which was not finished until after 
the war, was a giant with a 110-foot span and 
a body or hull 50 feet long. During the war 
seaplanes carried wireless telephone apparatus 
with which they could call to destroyers and sub- 
marine-chasers when they spotted a submarine. 
They also carried bombs which they could drop 
on U-boats, and even heavy guns with which 
they could fire shell. 

A still later development are the giant planes 
of the N. C. t}^pe with a wing-spread of 126 
feet and driven by four Liberty motors. They 
carry a useful load of four and a half tons. 

Early in the war, large guns were mounted 
on airplanes, but the shock of the recoil proved 
too much for the airplane to stand. However, 



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PZANMS 




(C) Underwood & Underwood 

The Flying-tank — an Armored German Airplane designed 
for firing on troops on the march 



■HBHB 







THE WAR IN THE AIR 145 

an American inventor produced a gun which 
had no recoil. This he accomplished by using 
a double-end gun, which was fired from the mid- 
dle. The bullet or shell was shot out at the 
forward end of the gun and a dummy charge 
of sand was shot out at the rear end. The sand 
spread out and did no damage at a short dis- 
tance from the gun, but care had to be taken 
not to come too close. These non-recoil guns 
were made in different sizes, to fire 1%-inch to 
3-inch shell. 

THE AUTOMATIC SEAPLANE 

Another interesting development was the tar- 
get airplane used for the training of aerial gun- 
ners. This was a small seaplane with a span 
of only 18% feet, driven by a 12-horse-power 
motor, the whole machine weighing but 175 
pounds. This was sent up without a pilot and 
it would fly at the rate of forty to fifty miles 
per hour until its supply of gasolene gave out, 
when it would drop down into the sea. It af- 
forded a real target for gunners in practice 
machines. 

Early in the war an American inventor pro- 
posed that seaplanes be provided with torpedoes 



146 INVENTIONS OF THE GREAT WAR 

which they could launch at an enemy ship. The 
seaplane would swoop down out of the sky to 
within a short distance of the ship, drop its pro- 
jecticle, and fly off again, and the torpedo would 
continue on its course until it blew up the vessel. 
It was urged that a fleet of such seaplanes pro- 
tected by a convoy of fast battle-planes could 
invade the enemy harbors and destroys its pow- 
erful fleet. It seemed like a rather wild idea, 
but the British actually built such torpedo- 
planes and tested them. However, the German 
fleet surrendered before it was necessary to 
blow it up in such fashion. 

AIRPLANES AFTER THE WAR 

With the war ended, all the Allied powers 
have large numbers of airplanes on their hands 
and also large numbers of trained aviators. 
Undoubtedly airplanes will continue to fill the 
skies in Europe and we shall see more and more 
of them in this country. Even during the war 
they were used for other purposes than fighting. 
There were ambulances on wings — machines 
with the top of the fuselage removable so that 
a patient on a stretcher could be placed inside. 
A French machine was furnished with a com- 



THE WAR IN THE AIR 147 

plete hospital equipment for emergency treat- 
ment and even for performing an operation in 
case of necessity. The flying hospital could 
carry the patient back to the field or base hos- 
pital after treatment. 

Mail-carrying airplanes are already an old 
story. In Europe the big bombing-machines 
are being used for passenger service between 
cities. There is an air line between Paris and 
London. The airplanes carry from a dozen to 
as man}^ as fifty passengers on a single trip. In 
some cities here, as well as abroad, the police 
are being trained to fly, so that they can police 
the heavens when the public takes to wings. 
Evidently the flying-era is here. 



OHAPTEE VIII 

Ships that Sail the Skies 

SHOETLY after the Civil War broke out, 
Thaddeus S. C. Lowe, an enthusiastic 
American aeronaut, conceived the idea of send- 
ing up scout balloons to reconnoiter the posi- 
tion of the enemy. These balloons were to be 
connected by telegraph wires with the ground, 
so that they could direct the artillery fire. The 
idea was so novel to the military authorities of 
that day that it was not received with favor. 
Balloons were looked upon as freak inventions, 
entirely impracticable for the stern realities 
of war ; and as for telegraphing from a balloon, 
no one had ever done that before. 

But this enthusiast was not to be daunted, 
and he made a direct appeal to President Lin- 
coln, offering to prove the practicability of this 
means of scouting. So he took his balloon to 
Washington and made an ascent from the 
grounds of the Smithsonian Institution, while 

148 




Courtesy of "Scientific American " 

Observation Car lowered from a Zeppelin sailing 
above the clouds 



SHIPS THAT SAIL THE SKIES 149 

the President came out on the lawn south of the 
White House to watch the demonstration. In 
order to test him, Mr. Lincoln took off his hat, 
waved his handkerchief, and made other signals. 
Lowe observed each act through his field-glasses 
and reported it to the President by telegraph. 
Mr. Lincoln was so impressed by the demonstra- 
tion that he ordered the army to use the ob- 
servation balloon, and so with some reluctance 
the gas-bag was introduced into military serv- 
ice, Professor Lowe being made chief aeronautic 
engineer. Under Lowe's direction the observa- 
tion balloons played an important part in the 
operations of the Union Army. 

On one occasion a young German military 
attache begged the privilege of making an as- 
cent in the balloon. Permission was given and 
when the German officer returned to earth he 
was wildly enthusiastic in praise of this aerial 
observation post. He had had a splendid view 
of the enemy and could watch operations 
through his field-glasses which were of utmost 
importance. Realizing the military value of 
the aircraft, he returned to Germany and urged 
military authorities to provide themselves with 
captive balloons. This young officer was Count 



150 INVENTIONS OF THE GREAT WAR 

Ferdinand von Zeppelin, who was destined later 
to become the most famous aeronautic authority 
in the world and who lived to see Germany 
equipped with a fleet of balloons which were 
self-propelling and could travel over land and 
sea to spread German f rightfulness into Eng- 
land. He also lived to see the virtual failure 
of this type of war-machine in the recent great 
conflict, and it was possibly because of his deep 
disappointment at having his huge expensive 
airships bested by cheap little airplanes that 
Count von Zeppelin died in March, 1917. How- 
ever, he was spared the humiliation of seeing a 
fleet of Zeppelins lose their way in a fog and 
fall into France, one of them being captured be- 
fore it could be destroyed, so that all its secrets 
of construction were learned by the French. 

THE WEIGHT OE HYDROGEN 

Before we describe the Zeppelin airships and 
the means by which they were eventually over- 
come, we must know something about the prin- 
ciples of balloons. Every one knows that bal- 
loons are kept up in the air by means of a very 
light gas, but somehow the general public fails 
to understand why the gas should hold it up. 



SHIPS THAT SAIL THE SKIES 151 

S»ome people have a notion that there is some- 
thing, mysterious about hydrogen gas which 
makes it resist the pull of gravity, and that the 
more hydrogen you crowd into the balloon the 
more weight it will lift. But hydrogen has 
weight and feels the pull of gravity just as air 
does, or water, or lead. The only reason the 
balloon rises is because it weighs less than the 
air it displaces. It is hard to think of air 
as having weight, but if we weigh air, hydrogen, 
coal-gas, or any other gas, in a vacuum, it will 
tip the scales just as a solid would. A thousand 
cubic feet of air weighs 80 pounds. In other 
words, the air in a room ten feet square with a 
ceiling ten feet high, weighs just about 80 
pounds. The same amount of coal-gas weighed 
in a vacuum would register only 40 pounds; 
while an equal volume of hydrogen would weigh 
only 5% pounds. But when we speak of vol- 
umes of gas we must remember that gas, unlike 
a liquid or a solid, can be compressed or ex- 
panded to almost any dimensions. For in- 
stance, we could easily fill our room with a ton 
of air if the walls would stand the pressure ; or 
we could pump out the air, until there were but 
a few ounces of air left. But in one case the 



152 INVENTIONS OF THE GREAT WAR 

air would be so' highly compressed that it would 
exert a pressure of about 375 pounds on every 
square inch of the wall of the room, while in 
the other case its pressure would be almost in- 
finitesimal. But 80 pounds of air in a room 
of a thousand cubic feet would exert the same 
pressure as the atmosphere, or 15 pounds on 
every square inch. And when we say that a 
thousand cubic feet of hydrogen weighs only a 
little over 5 pounds, we are talking about hydro- 
gen at the same pressure as the atmosphere. 

Since the hydrogen is sixteen times lighter 
than air, naturally it will float in the air, just as 
a piece of wood will float in water because it is 
lighter than the same volume of water. If we 
surrounded the thousand cubic feet of hydro- 
gen with a bag so that the gas will not diffuse 
into the air and mix with it, we shall have a 
balloon which would float in air provided the bag 
and the hydrogen it contains do not weigh more 
than eighty pounds. As we rise from the sur- 
face of the earth, the air becomes less and less 
dense, or, in other words, it becomes lighter, 
and the balloon will keep on rising through the 
atmosphere until it reaches a point at which its 



SHIPS THAT SAIL THE SKIES 153 

weight, gas-bag and all, is exactly the same as 
that of an equal volume of air. 

But there are many conditions that affect the 
height to which the balloon will ascend. The 
higher we rise, the colder it is apt to become, 
and cold has a tendency to compress the hydro- 
gen, collapsing the balloon and making it rela- 
tively heavier. When the sun beats upon a bal- 
loon, it heats the hydrogen, expanding it and 
making it relatively lighter, and if there is 
no room for this expansion to take place in the 
bag, the bag will burst. For this reason, a big 
safety-valve must be provided and the ordinary 
round balloon is open at the bottom so that the 
hydrogen can escape when it expands too much 
and the balloonist carries ballast in the form of 
sand which he can throw over to lighten the 
balloon when the gas is contracted by a sudden 
draft of cold air. 

Although a round balloon carries no engine 
and no propeller, it can be guided through the 
air to some degree. When an aeronaut wishes 
to go in any particular direction, he sends up 
his balloon by throwing out ballast or lowers it 
by letting out a certain amount of gas, until 



154 INVENTIONS OF THE GBEAT WAR 

he reaches a level at which he finds a breeze 
blowing in the desired direction. Such was 
the airship of Civil War times, but for mili- 
tary purposes it was not advisable to use free 
balloons, because of the difficulty of controlling 
them. They were too liable to fall into the 
hands of the enemy. All that was needed was 
a high observation post from which the enemy 
could be watched, and from which observations 
could be reported by telegraph. The balloon 
was not looked upon as a fighting-machine. 

Zeppelin's failures and successes 

But Count Zeppelin was a man of vision. He 
dreamed of a real ship of the air — a machine 
that would sail wherever the helmsman chose, 
regardless of wind and weather. Many years 
elapsed before he actually began to work out 
his dreams, and then he met with failure after 
failure. He believed in big machines and the 
loss of one of his airships meant the waste of 
a large sum of money, but he persisted, even 
though he spent all his fortune, and had to go 
heavily in debt. Every one thought him a crank 
until he built his third airship and proved its 
worth by making a trip of 270 miles. At once 



SHIPS THAT SAIL THE SKIES 155 

the German Government was interested and saw 
wonderful military possibilities in the new craft. 
The Zeppelin was purchased by the government 
and money was given the inventor to further his 
experiments. 

That was not the end of his failures. Before 
the war broke out, thirteen Zeppelins had been 
destroyed by one accident or another. Evi- 
dently the building of Zeppelin airships was not 
a paying undertaking, although they were used 
to carry passengers on short aerial voyages. 
But the government made up money losses and 
Zeppelin went on developing his airships. 

Of course, he was not the only one to build 
airships, nor even the first to build a dirigible. 
The French built some large dirigibles, but 
they failed to see any great military advantage 
in ships that could sail through the air, par- 
ticularly after the airplane was invented, and 
so it happened that when the war started the 
French were devoting virtually all their ener- 
gies to the construction of speedy, powerful 
airplanes. As for the British, they did not pay 
much attention to airships. The idea that their 
isles might be attacked from the sky seemed an 
exceedingly remote possibility. 



156 INVENTIONS OF THE GBEAT WAR 

RIGID, SEMI-RIGID, AND FLEXIBLE BALLOONS 

Count Zeppelin always held that the dirigible 
balloons must be rigid, so that they could be 
driven through the air readily and would hold 
their shape despite variations in the pressure of 
the hydrogen. The French, on the other hand, 
used a semi-rigid airship ; that is, one in which a 
flexible balloon is attached to a rigid keel or 
body. The British clung to the idea of an en- 
tirely flexible balloon and they suspended their 
car from the gas-bag without any rigid frame- 
work to hold the gas-bag in shape. In every 
case, the balloons were kept taut or distended 
by means of air-bags or ballonets. These air- 
bags were placed inside the gas-bags and as the 
hydrogen expanded it would force the air out 
through valves, but the hydrogen itself would 
not escape. When the hydrogen contracted, the 
air-bags were pumped full of air so as to main- 
tain the balloon in its fully distended condition. 
Additional supplies of compressed hydrogen 
were kept in metal tanks. 

In the Zeppelin balloon, however, the gas was 
contained in separate bags which were placed in 
a framework of aluminum covered over with 




(C) Underwood & Underwood 

Giant British Dirigible built along the lines of a Zeppelin 




(C) Underwood & Underwood 

One of the engine cars or "power eggs" of a British Dirigible 



SHIPS THAT SAIL THE SKIES 157 

fabric. Count Zeppelin did not believe in plac- 
ing all bis eggs in one basket. If one of these 
balloons burst or was injured in any way, there 
was enough buoyancy in the rest of the gas-bags 
to hold up the airship. As the Zeppelins were 
enormous structures, the framework had to be 
made strong and light, and it was built up of a 
latticework of aluminum alloy. Aluminum it- 
self was not strong enough for the purpose, but 
a mixture of aluminum and zinc and later an- 
other alloy known as duralumin, consisting of 
aluminum with three per cent of copper ,and 
one per cent of nickel, provided a very rigid 
framework that was exceedingly light. Dura- 
lumin is four or five times as strong as alum- 
inum and yet weighs but little more. 

The body of the Zeppelin is not a perfect cir- 
cle in section, but is made up in the form of a 
polygon with sixteen sides, and the largest of the 
Zeppelins used during the war contained sixteen 
compartments, in each of which was placed a 
large hydrogen gas-bag. A super-Zeppelin, as 
the latest type is called, was about seventy-five 
feet in diameter and seven hundred and sixty 
feet long, or almost as long as three New 
York street blocks. In its gas-bags it carried 



158 INVENTIONS OF THE GREAT WAR 

two million cubic feet of hydrogen and although 
the whole machine with its fuel, stores, and pas- 
sengers weighed close to fifty tons, it was so 
much lighter than the air it displaced that it 
had a reserve buoyancy of over ten tons. 

KEEPING ENGINES CLEAR OE THE INFLAMMABLE 
HYDROGEN 

As hydrogen is a very inflammable gas, it is 
extremely dangerous to have an internal-com- 
bustion engine operating very near the gas- 
bags. In the super-Zeppelins the engines were 
placed in four cars suspended from the balloon. 
There was one of these cars forward, and one 
at the stern, while near the center were two cars 
side by side. In the rear car there were two 
engines, either of which could be used to drive 
the propeller. By means of large steering rud- 
ders and horizontal rudders, the machine could 
be forced to dive or rise or turn in either direc- 
tion laterally. The pilot of the Zeppelin had 
an elaborate operating-compartment from 
which he could control the rudders, and he also 
had control of the valves in the ballonets so that 
by the touch of a button he could regulate the 
pressure of gas in any part of the dirigible. 



SHIPS THAT SAIL THE SKIES 159 

There were nineteen men in the crew of the 
Zeppelin — two in the operating-compartment, 
and two in each of the cars containing engines, 
except for the one at the stern in which there 
were three men. The other men were placed 
in what was known as the "cat walk" or pass- 
ageway running inside the framework under 
the gas-bags. These men were given various 
tasks and were supposed to get as much sleep 
as they could, so as to be ready to replace the 
other men at need. 

The engine cars at each side of the balloon 
were known as power eggs because of their gen- 
eral egg shape. At the center of the Zeppelin 
the bombs were stored, and there were electro- 
magnetic releasing-devices operated from the 
pilot's room by which the pilot could drop the 
bombs whenever he chose. The Zeppelin also 
carried machine-guns to fight off airplanes. 
Gasolene was stored in tanks which were placed 
in various parts of the machine, any one of 
which could feed one or all of the engines, and 
they were so arranged that they could be thrown 
overboard when the gasolene was used up, so 
as to lighten the load of the Zeppelin. Water 
ballast was used instead of sand, and alcohol 



160 INVENTIONS OF THE GEEAT WAR 

was mixed with the water to keep it from freez- 
ing. The machine which came down in French 
territory and was captured before it could be 
destroyed by the pilot, found itself unable to 
rise because in the intense cold of the upper 
air the water ballast had frozen, and it could 
not be let out to lighten the load of the Zep- 
pelin. 



The one thing above all others that the Zep- 
pelin commander feared was the attack of air- 
planes. In the early stages of the war, it was 
considered unsafe for airplanes to fly by night 
because of the difficulty of making a landing in 
the dark. Later this difficulty was overcome by 
the use of search-lights at the landing-fields. 
The airplane would signal its desire to land and 
the search-lights would point out the proper 
landing-field for it. So that after the first few 
months of the war Zeppelins were subjected to 
the danger of airplane attack. Of course, on a 
dark night it was very difficult for an airplane 
to locate a Zeppelin, because the huge machine 
could not be seen and the throb of its engines 
was drowned out by the engines of the airplane 






<u 




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C 


CO 


03 


o 



IPI1 




SHIPS THAT SAIL THE SKIES 161 

itself. Nevertheless, Zeppelins were occa- 
sionally located and destroyed by airplanes. 

The danger of the Zeppelin lay in the fact 
that it was supported by an enormous volume 
of very inflammable gas and the airplane needed 
but to set fire to this gas to cause the destruc- 
tion of the giant of the air. And so the ma- 
chine-guns carried by airplanes were provided 
with explosive, flaming bullets. A burst of 
flame within the gas-bag would not set the gas 
on fire, because there would be no air inside 
to feed the fire, but surrounding the gas-bag 
there was always a certain leakage of hydro- 
gen which would mix with the air in the com- 
partment and this would produce an explosive 
mixture which needed but the touch of fire to 
set it off. The Zeppelin was provided with a 
ventilating-system to carry off these explosive 
gases, but they could never be disposed of very 
effectively, and, as a consequence, a number of 
Zeppelins were destroyed by the tiny antagon- 
ists that were sent up by the British and the 
French. To fight off these assailants the Ger- 
mans provided their Zeppelins with guns which 
would fire shrapnel shell. It is difficult for a 
Zeppelin to use machine-guns against an air- 



162 INVENTIONS OF THE GREAT WAR 

plane because the latter would merely climb 
above the Zeppelin and would be shielded by 
the balloon itself. And so the Germans put a 
gun emplacement on top of the balloon both 
forward and aft. There was a deck extending 
along the top of the balloon which was reached 
by a ladder running up through the center of 
the airship. But it was impossible to ward off 
the fleet little antagonists, once the dirigible was 
discovered. True, a Zeppelin could make as 
much as seventy miles per hour, but the fast- 
est airplanes could travel twice as fast as that. 

SUSPENDING AN OBSERVER BELOW THE ZEPPELIN 

One ingenious scheme that was tried was to 
suspend an observation car under the Zeppelin. 
The car was about fourteen feet long and five 
feet in diameter, fitted with a tail to keep it 
headed in the direction it was towed. It had 
glass windows forward and there was plenty of 
room in it for a man to lie at full length and 
make observations of things below. The car 
with its observer could be lowered a few thou- 
sand feet below the Zeppelin, so that the ob- 
server could watch proceedings below, while the 
airship remained hidden among the clouds. 



SHIPS THAT SAIL THE SKIES 163 

The observer was connected by telephone with 
the chart-room of the Zeppelin and could report 
his discoveries or even act as a pilot to direct 
the course of the ship. 

But despite everything that could be done, 
the Zeppelin eventually proved a failure as a 
war-vessel because it was so very costly to con- 
struct and operate and could so easily be de- 
stroyed, and the Germans began to build huge 
airplanes with which bombing-raids could be 
continued. 

Strange to say, however, although the Ger- 
mans were ready to admit the failure of their 
big airship, when the war stopped the Allies 
were actually building machines patterned after 
the Zeppelin, but even larger, and expected to 
use them for bombing-excursions over Ger- 
many. This astonishing turn of the tables was 
due to the fact that America had made a con- 
tribution to aeronautics that solved the one 
chief drawback of the Zeppelin. 

A BALLOON GAS THAT WILL NOT BUEN 

When we entered the war against Germany, 
our allies placed before us all their problems 
and among them was this one of the highly in- 



164 INVENTIONS OF THE GREAT WAR 

flammable airship. Could we not furnish a sub- 
stitute for hydrogen that would not burn? It 
was suggested to us that helium would do if we 
could produce that gas cheaply and in sufficient 
quantity. Now, helium has a history of its own 
that is exceedingly interesting. 

Every now and then the moon bobs its head 
into our light and we have a solar eclipse. But 
our satellite is not big enough to cut off all 
the light of the big luminary and the fiery at- 
mosphere of the sun shows us a brilliant halo 
all around the black disk of the moon. Long 
ago, astronomers analyzed this flaming atmos- 
phere with the spectroscope, and by the differ- 
ent bands of light that appeared they were able 
to determine what gases were present in the 
sun's atmosphere. But there was one band of 
bright yellow which they could not identify. 
Evidently this was produced by a gas unknown 
on earth, and they called it "helium" or "sun" 
gas. 

For a quarter of a century this sun gas re- 
mained a mystery; then one day, in 1895, Sir 
William Kamsay discovered the same band of 
light when studying the spectrum of the mineral 
cleveite. The fact that astronomers had been 



SHIPS THAT SAIL THE SKIES 165 

able to single out an element on the sun ninety 
million miles away before our chemists could 
find it right here on earth, produced a mild sen- 
sation, but the general public attached no spe- 
cial importance to the gas itself. It proved 
to be a very light substance, next to hydrogen 
the lightest of gases, and for years it resisted 
all attempts at liquefaction. Only when Onnes, 
the Dutch scientist, succeeded in getting it down 
to a temperature of 450 degrees below zero, Fah- 
renheit, did the gas yield to the chill and con- 
dense into a liquid. The gas would not burn; 
it would not combine with any other elements, 
and apparently it had no use on earth, and it 
might have remained indefinitely a lazy member 
of the chemical fraternity had not the great 
world conflict stirred us into frenzied activity 
in all branches of science in our effort to beat 
the Hun. 

Because the gas had no commercial value, 
there was only a small amount of helium to be 
found in the whole world. Not a single labora- 
tory in the United States had more than five 
cubic feet of it and its. price ranged from 
$1,500 to $6,000 per cubic foot. At the lowest 
price it would cost $3,000,000,000 to provide gas 



166 INVENTIONS OF THE GREAT WAR 

enough for one airship of Zeppelin dimensions 
and it seemed absurd even to think of a helium 
airship. 

AMEEICAN CHEMISTS TO THE EESCUE 

Just before the war it was discovered that 
there is a considerable amount of helium in the 
natural gas of Oklahoma, Texas, and Kansas, 
and Sir William Ramsey suggested that our 
chemists might study some method of getting 
helium from this source. The only way of sep- 
arating it out was to liquefy the gases by sub- 
jecting them to extreme cold. All gases turn 
to liquid if they are cooled sufficiently, and then 
further cold will freeze them solid. But helium 
can stand more cold than any other and this 
fact gave the clue to its recovery from natu- 
ral gas. The latter was frozen and one after 
another the different elements condensed into 
liquid, until finally only helium was left. 
This sounds simple, but it is a difficult mat- 
ter to get such low temperature as that on a 
large scale and do it economically. To be of 
any real service in aeronautics helium would 
have to be reduced in cost from fifteen hun- 
dred dollars to less than ten cents per cubic 



SHIPS THAT SAIL THE SKIES 167 

foot. Several different kinds of refrigerating- 
machinery were tried and finally just before the 
war was brought to a close by the armistice we 
had succeeded in producing helium at the rate 
of eight cents per cubic foot, with the prospect 
of reducing its cost still further. A large plant 
for recovering helium was being built. The 
plant will have been completed before this book 
is published, and it will be turning out helium 
for peaceful instead of military airships. 

The reduction in the cost of helium is really 
one of the most important developments of this 
war. By removing the fire risk from airships 
we can safely use these craft for aerial cruises 
or for quick long-distance travel over land and 
sea. For, even in time of peace, sailing under 
millions of cubic feet of hydrogen is a serious 
matter. Although no incendiary bullets are to 
be feared, there is always the danger of setting 
fire to the gas within the exhaust of the engines. 
Engines have had to be hung in cars well below 
the balloon proper. But with helium in the gas- 
bags the engines can be placed inside the bal- 
loon envelop and the propellers can operate on 
the center line of the car. 

In the case of one Zeppelin, the hydrogen was 



168 INVENTIONS OF THE GREAT WAR 

set on fire by an electric spark produced by fric- 
tion on the fabric of one of the gas-bags, and so 
even with the engine exhausts properly screened 
there is danger. The helium airship, however, 
would be perfectly safe from fire and passen- 
gers could smoke on deck or in their cabins 
within the balloon itself without any more fear 
of fire than they would have on shipboard. 
Wonderful possibilities have been opened by the 
production of helium on a large and economical 
scale, and the airship seems destined to play 
an important part in transportation very soon. 
As this book is going to press, we learn of enor- 
mous dirigibles about to be built in England for 
passenger service, which will have half again as 
great a lifting-power as the largest Zeppelins. 
The final chapter of the story of dirigibles is yet 
to be written, but in concluding this chapter it 
is interesting to note that the world's greatest 
aeronautic expert got his first inspiration from 
America and finally that America has now fur- 
nished the one element which was lacking to 
make the dirigible balloon a real success. 



CHAPTER IX 
Getting the Range 

EVERY person with a good pair of eyes in 
his head is a range-finder. He may not 
know it, but he is, just the same, and the way to 
prove it is to try a little range-finding on a small 
scale. 

Use the top of a table for your field of opera- 
tions, and pick out some spot within easy reach 
of your hand for the target whose range you 
wish to find. The target may be a penny or a 
small circle drawn on a piece of white paper. 
Take a pencil in your hand and imagine it is 
a shell which you are going to land on the 
target. It is not quite fair to have a bird's-eye 
view of the field, so get down on your knees and 
bring your eyes within a few inches of the top 
of the table. Now close one eye and making 
your hand describe an arc through the air, like 
the arc that a shell would describe, see how 
nearly you can bring the pencil-point down on 

169 



170 INVENTIONS OF THE GREAT WAR 

the center of the target. Do it slowly, so that 
your eye may guide the hand throughout its 
course. You will be surprised to find out how 
far you come short, or overreach the mark. 
You will have actually to grope for the target. 
If by any chance you should score a hit on the 
first try, you may be sure that it is an accident. 

Have a friend move the target around to a 
different position, and try again. Evidently, 
with one eye you are not a good range-finder; 
but now use two eyes and you will score a hit 
every time. Not only can you land the pencil 
on the penny, but you will be able to bring it 
down on the very center of the target. 

The explanation of this is- that when you 
bring your eyes to bear upon any object that 
is near by, they have to be turned in slightly, so 
that both of them shall be aimed directly at 
that object. The nearer the object, the more 
they are turned in, and the farther the object, 
the more nearly parallel are the eyes. Long 
experience has taught you to gage the distance 
of an object by the feel of the eyes — that is, by 
the effort your muscles have to make to pull 
the eyes to a focus — and in this way the eyes 
give you the range of an object. You do not 



GETTING THE RANGE 171 

know what the distance is in feet or inches, but 
you can tell when the pencil-point has moved 
out until it is at the same focus as the target. 
The experiment can be tried on a larger scale 
with the end of a fishing-rod, but here you will 
probably have to use a larger target. However, 
there is a limit to which you can gage the range. 
At a distance of, say, fifteen or twenty feet, a 
variation of a few inches beyond or this side 
of the target makes scarcely any change in the 
focus of the eyes. That is because the eyes are 
so close together. If they were farther apart, 
they could tell the range at much greater dis- 
tances. 

SPREADING THE EYES FAR APART 

Now the ordinary range-finder, used in the 
army and in the navy, is an arrangement for 
spreading the eyes apart to a considerable dis- 
tance. Of course the -eyes are not actually 
spread, but their vision is. The range-finder is 
really a double telescope. The barrel is not 
pointed at an object, but it is held at right angles 
to it. You look into the instrument at the mid- 
dle of the barrel and out of it at the two ends. 
A system of mirrors or prisms makes this pos- 



172 INVENTIONS OF THE GREAT WAR 

sible. The range-finder may be a yard or more 
in length, which is equivalent to spreading your 
eyes a yard or more apart. Now, the prisms or 
object-glasses at the ends of the tube are ad- 
justable, so that they will turn in until they 
focus directly on the target whose range you 
wish to find, and the angle through which these 
glasses are turned gives a measure of the dis- 
tance of the target. The whole thing is cal- 
culated out so that the distance in feet, yards, 
or meters, or whatever the measure may be, is 
registered on a scale in the range-finder. Ordi- 
narily only one eye is used to look through the 
range-finder, because the system of mirrors is 
set to divide the sight of that one eye and make 
it serve the purposes of two. That leaves the 
other eye free to read the scale, which comes 
automatically into view as the range-finder is 
adjusted for the different ranges. 

On the battle-ships enormous range-finders 
are used. Some of them are twenty feet long. 
With the eyes spread as far apart as that and 
with a microscope to read the scale, you can 
imagine how accurately the range can be found, 
even when the target is miles away. But on 
land such big range-finders cannot conveniently 



GETTING THE RANGE 173 

be used; they are too bulky. When it is neces- 
sary to get the range of a very distant object, 
two observers are used who are stationed sev- 
eral hundred yards apart. These observers 
have telescopes which they bear upon the ob- 
ject, and the angle through which they have to 
turn the telescope is reported by telephone to 
the battery, where, by a rapid calculation, it is 
possible to estimate the exact position of the 
target. Then the gun is moved up or down, to 
the right or to the left, according to the cal- 
culation. The observers have to creep as near 
to the enemy as possible and they must be up 
high enough to command a good view o£ the 
target. Sometimes they are placed on top of 
telegraph poles or hidden up a tall tree, or in 
a church steeple. 

GETTING THE OBSERVER OFF THE GROUND 

This was the method of getting the range in 
previous wars and it was used to a considerable 
extent in the war we have just been through. 
But the great European conflict brought out 
wonderful improvements in all branches of 
fighting; and range-finding was absolutely rev- 
olutionized, because shelling was done at greater 



174 INVENTIONS OF THE GREAT WAR 

ranges than ever before, but chiefly because the 
war was carried up into the sky. 

A bird's-eye observation is much more ac- 
curate than any that can be obtained from the 
ground. Even before this war, some observa- 
tions were taken by sending a man up in a kite, 
particularly a kite towed from a ship, and even 
as far back as the Civil War captive balloons 
were used to raise an observer to a good height 
above the ground. They were the ordinary 
round balloons, but the observation balloon of 
to-day is a very different-looking object. It is 
a sausage-shaped gas-bag that is held on a slant 
to the wind like a kite, so that the wind helps 
to hold it up. To keep it head-on to the wind, 
there is a big air-bag that curls around the 
lower end of the sausage. This acts like a rud- 
der, and steadies the balloon. Some balloons 
have a tail consisting of a series of cone-shaped 
cups strung on a cable. A kite balloon will ride 
steadily in a wind that would dash a common 
round balloon in all directions. Observers in 
these kite balloons are provided with telephone 
instruments by which they can communicate in- 
stantly with the battery whose fire they are di- 
recting. But a kite balloon is a helpless object; 



GETTING THE RANGE 175 

it cannot fight the enemy. The hydrogen gas 
that holds it up will burn furiously if set on 
fire. In the war an enemy airplane had merely 
to drop a bomb upon it or fire an incendiary bul- 
let into it, and the balloon would go up in smoke. 
Nothing could save it, once it took fire, and all 
the observers could do was to jump for their 
lives as soon as they saw the enemy close by. 
They always had parachutes strapped to them, 
so they could leap without an instant's delay in 
case of sudden danger. At the very first ap- 
proach of an enemy airplane, the kite balloon 
had to be hauled down or it would surely be de- 
stroyed, and so kite balloons were not very de- 
pendable observation stations for the side 
which did not control the air. 

As stated in the preceding chapter, just be- 
fore the fighting came to an end, our army was 
preparing to use balloons that were not afraid 
of flaming bullets, because they were to be filled 
with a gas that would not burn. 

MAKING MAPS WITH A CAMERA 

Because airplanes filled the sky with eyes, 
everything that the army did near the front 
had to be carefully hidden from the winged 



176 INVENTIONS OF THE GREAT WAR 

scouts. Batteries were concealed in the woods, 
or under canopies where the woods were shot 
to pieces, or they were placed in dugouts so that 
they could not be located. Such targets could 
seldom be found with a kite balloon. It was 
the task of airplane observers to search out 
these hidden batteries. The eye alone was not 
depended upon to find them. Large cameras 
were used with telescopic lenses which would 
bring the surface of the earth near while the 
airplane flew at a safe height. These we-re 
often motion-picture cameras which would auto- 
matically make an exposure every second, or 
every few seconds. 

When the machine returned from a photo- 
graphing-expedition, the films were developed 
and printed, and then pieced together to form a 
photographic map. The map was scrutinized 
very carefully for any evidence of a hidden bat- 
tery or for any suspicious enemy object. As 
the enemy was always careful to disguise its 
work, the camera had to be fitted with color- 
screens which would enable it to pick out de- 
tails that would not be evident to the eye. As 
new photographic maps were made from day to 
day, they were carefully compared one with 



GETTING THE RANGE 177 

the other so that it might be seen if there was the 
slightest change in them which would indicate 
some enemy activity. As soon as a suspicious 
spot was discovered, its position was noted on 
a large-scale military map and the guns were 
trained upon it. 

CORRECTING THE AIM 

It is one thing to know where the target is and 
another to get the shell to drop upon it. In the 
firing of a shell a distance of ten or twenty miles, 
the slightest variation in the gun will make a 
difference of many yards in the point where the 
shell lands. Not only that, but the direction of 
the wind and the density of the air have a part 
to play in the journey of the shell. If the shell 
traveled through a vacuum, it would be a much 
simpler matter to score a hit by the map alone. 
But even then there would be some differences, 
because a gun has to be "warmed up" before it 
will fire according to calculation. That is why 
it is necessary to have observers, or " spotters' ? 
as they are called, to see where the shell actu- 
ally do land and tell the gun-pointers whether 
to elevate or depress the gun, and how much to 
' ' traverse ' ' it — that is, move it sideways. This 



178 INVENTIONS OF THE GREAT WAR 

would not be a very difficult matter if there 
were only one gun firing, but when a large num- 
ber of guns are being used, as was almost in- 
variably the case in the war, the spotter had to 
know which shell belonged to the gun he was 
directing. 

One of the most important inventions of the 
war was the wireless telephone, which airplanes 
used and which were brought to such perfection 
that the pilot of an airplane could talk to a 
station on the earth without any difficulty, 
from a distance of ten miles; and in some 
cases he could reach a range of fifty miles. 
With the wireless telephone, the observer could 
communicate instantly with the gun-pointer, 
and tell him when to fire. Usually -thirty sec- 
onds were allowed after the signal sent by the 
observer before the gun was fired, and on the in- 
stant of firing, a signal was sent to the man in 
the airplane to be on the lookout for the shell. 
Knowing the position of the target, the gun- 
pointer would know how long it would take the 
shell to travel through the air, and he would 
keep the man in the airplane posted, warning 
him at ten seconds, five seconds, and so forth, 
before the shell was due to land. 



GETTING THE RANGE 179 

In order to keep the eyes fresh for observation 
and not to have them distracted by other sights, 
the observer usually gazed into space until just 
before the instant the shell was to land. Then 
he would look for the column of smoke pro- 
duced by the explosion of the shell and report 
back to the battery how far wide of the mark 
the shell had landed. A number of shell would 
be fired at regular intervals, say four or five per 
minute, so that the observer would know which 
shell belonged to the gun in question. 

There are different kinds of shell. Some 
will explode on the instant of contact with the 
earth. These are meant to spread destruction 
over the surface. There are other shell which 
will explode a little more slowly and these pene- 
trate the ground to some extent before going off ; 
while a third type has a delayed action and is 
intended to be buried deep in the ground before 
exploding, so as to destroy dugouts and under- 
ground positions. The bursts of smoke from 
the delayed-action shell and the semi-delayed- 
action shell rise in a slender vertical column and 
are not so easily seen from the sky. The instan- 
taneous shell, however, produces a broad burst 
of smoke which can be spotted much more 



180 INVENTIONS OF THE GREAT WAR 

readily, and this enables the man in the air- 
plane to determine the position of the shell with 
greater accuracy. For this reason, instantan- 
eous shell were usually used for spotting-pur- 
poses, and after the gun had found its target, 
other shell were used suited to the character of 
the work that was to be done. 

MINIATURE BATTLE-FIELDS 

Observation of shell-fire from an airplane 
called for a great deal of experience, and our 
spotters were given training on a miniature 
scale before they undertook to do spotting from 
the air. A scaffolding was erected in the train- 
ing-quarters over a large picture of a typical bit 
of enemy territory. Men were posted at the 
top of this scaffolding so that they could get a 
bird's-eye view of the territory represented on 
the map, and they were connected by telephone 
or telegraph with men below who represented 
the batteries. The instructor would flash a little 
electric light here and there on the miniature 
battle-field, and the observers had to locate these 
flashes and tell instantly how far they were 
from certain targets. This taught them to be 
keen and quick and to judge distance accurately. 






GETTING THE RANGE 181 



Airplane observing was difficult and dangerous, 
and often impossible. On cloudy days the ob- 
server might be unable to fly at a safe height 
without being lost in the clouds. Then depend- 
ence had to be placed upon observers stationed 
at vantage-points near the enemy, or in kite 
balloons. 

SPOTTING BY SOUND 

When there is no way of seeing the work of 
a gun, it is still possible to correct the aim, be- 
cause the shell can be made to do its own spot- 
ting. Every time a shell lands, it immediately 
announces the fact with a loud report. That 
report is really a message which the shell sends 
out in all directions with a speed of nearly 800 
miles per hour — 1,142 feet per second, to be 
exact. This sound-message is picked up by a 
recorder at several different receiving-stations. 
Of course it reaches the nearest station a frac- 
tion of a second before it arrives at the next 
nearest one. The distance of each station from 
the target is known by careful measurement on 
the map, and the time it takes for sound to 
travel from the target to each station is accur- 
ately worked out. If the sound arrives at each 



182 INVENTIONS OF THE GREAT WAR 

station on schedule time, the shell has scored a 
hit; but if it reaches one station a trifle ahead 
of time and lags behind at another, that is evi- 
dence that the shell has missed the target and a 
careful measure of the distance in time shows 
how far and in what direction it is wide of the 
mark. In this way it was possible to come 
within fifty or even twenty-five yards of the 
target. ' 

This sound-method was also used to locate 
an enemy battery. It was often well nigh im- 
possible to locate a battery in any other way. 
With the use of smokeless powder, there is 
nothing to betray the position of the gun, ex- 
cept the flash at the instant of discharge, and 
even the flash was hidden by screens from the 
view of an airplane. Aside from this, when an 
airplane came near enough actually to see one 
of these guns, the gun would stop firing until the 
airplane had been driven off. But a big gun 
has a big voice, and it is impossible to silence 
it. Often a gun whose position has remained 
a secret for a long time was discovered because 
the gun itself " peached.' ' 

The main trouble with sound- spotting was 
that there were usually so many shell and guns 



GETTING THE RANGE 183 

going off at the same time that it was difficult 
if not impossible to distinguish one from an- 
other. Sometimes the voice of a hidden gun 
was purposely drowned by the noise of a lot of 
other guns. After all, the main responsibility 
for good shooting had to fall on observers who 
could actually see the target, and when we think 
of the splendid work of our soldiers in the war, 
we must not forget to give full credit to the 
tireless men whose duty it was to watch, to 
the men on wings who dared the fierce battle- 
planes of the enemy, to the men afloat high in 
the sky who must leap at a moment's notice 
from under a blazing mass of hydrogen, and 
finally to the men who crept out to perilous 
vantage-points at risk of instant death, in order 
to make the fire of their batteries tell. 



OHAPTEE X 

Talking in the Sky 

IN one field of war invention the United States 
held almost' a monopoly and the progress 
Americans achieved was epoch-making. 

Before the war, an aviator when on the wing 
was both deaf and dumb. He could communi- 
cate with other airplanes or with the ground 
only by signal or, for short distances, by radio- 
telegraphy, but he could not even carry on 
conversation with a fellow passenger in the 
machine without a speaking-tube fitted to mouth 
and ears so as to cut out the terrific roar of 
his own engine. Now the range of his voice 
has been so extended that he can chat with fel- 
low aviators miles away. This remarkable 
achievement and many others in the field of 
radio-communication hinge upon a delicate elec- 
trical device invented by Deforest in 1906 and 
known as the "audion." For years this in- 
strument was used by radiotelegraphers with- 

184 



TALKING IN THE SKY 185 

out a real appreciation of its marvelous possi- 
bilities, and, as a matter of fact, in its earlier 
crude form it was not capable of performing the 
wonders it has achieved since it was taken over 
and developed by the engineers of the Bell Tele- 
phone System. 

THE AUDION 

Although the audion is familiar to all ama- 
teur radio-operators, we shall have to give a 
brief outline of its construction and operation 
for the benefit of those who have not had the 
opportunity to dabble in wireless telegraphy. 

The audion is a small glass bulb from which 
the air is exhausted to a high degree of vacuum. 
The bulb contains three elements. One is a 
tiny filament which is heated to incandescence 
by a battery, so that it emits negatively charged 
electrons. The filament is at one side of the 
bulb and at the opposite side there is a metal 
plate. When the plate and the filament are 
connected with opposite poles of a battery, there 
is a flow of current between them, but because 
only negative electrons are emitted by the 
filament, the current will flow only in one di- 
rection — that is, from the plate to the filament. 



186 INVENTIONS OF THE GREAT WAR 

If the audion be placed in the circuit of an alter- 
nating-current generator, it will let through 
only the current running in one direction. 
Thus it will "rectify" the current or convert 
alternating current into direct current. 

But the most important part of the audion, the 
part for which Deforest is responsible, is the 
third element, which is a grid or flat coil of 
platinum wire placed between the filament and 
the plate. This grid furnishes a very delicate 
control of the strength of the electric current 
between plate and filament. The slightest 
change in electric power in the grid will pro- 
duce large changes of power in the current 
flowing through the audion. This makes it 
possible to magnify or amplify very feeble elec- 
tric waves, and the extent to which the ampli- 
fying can be carried is virtually limitless, be- 
cause a series of audions can be used, the cur- 
rent passing through the first being connected 
with the grid of the next, and so on. 

TALKING FEOM NEW YORK TO SAN FRANCISCO 

There is a limit to which telephone conversa- 
tions can be carried on over a wire, unless there 
is some way of adding fresh energy along the 



TALKING IN THE SKY 187 

line. For years all sorts of experiments were 
tried with mechanical devices which would re- 
ceive a telephone message and send it on with 
a fresh relay of current. But these devices dis- 
torted the message so that it was unintelligible. 
The range of wire telephony was greatly in- 
creased by the use of certain coils invented by 
Pupin, which were placed in the line at inter- 
vals; but still there was a limit to which con- 
versation could be carried on by wire and it 
looked as if it would never be possible to tele- 
phone from one end of this big country of ours 
to the other. But the audion supplied a 
wonderfully efficient relay and one day we 
awoke to hear San Francisco calling, "Hello," 
to New York. 

Used as a relay, the improved audion made it 
possible to pick up very faint wireless-tele- 
graph messages and in that way increased the 
range of radio outfits. Messages could be re- 
ceived from great distances without any exten- 
sive or elaborate aerials, and the audion could 
be used at the sending-station to magnify the 
signals transmitted and send them forth with 
far greater power. 

Having improved the audion and used it sue- 



188 INVENTIONS OF THE GREAT WAR 

cessfully for long-distance telephone conversa- 
tion over wires, the telephone company began 
to experiment with wireless telephony. They 
believed that it might be possible to use radio- 
telephony in places where wires could not be 
laid. For instance, it might be possible to talk 
across the Atlantic. 

But before we go farther, just a word of ex- 
planation concerning radiotelegraphy and radio- 
telephony for the benefit of those who have 
not even an elementary knowledge of the 
subject. 

SIMPLE EXPLANATION OF EADIOTELEGEAPHY 

Suppose we should set up two stakes in a pond 
of water, at some distance from each other, and 
around each we set a ring-shaped cork float. If 
we should move one of these floats up and down 
on its stake, it would produce ripples in the 
water which would spread out in all directions 
and finally would reach the opposite stake and 
cause the float there to bob up and down in 
exactly the same way as did the float moved 
by hand. In wireless telegraphy the two stakes 
are represented by antennae or aerials and the 
cork floats are electric charges which are sent 



TALKING IN THE SKY 189 

oscillating up and down the antennas. The os- 
cillations produced at one aerial will set up 
electro-magnetic waves which will spread out 
in all directions in the ether until they reach a 
receiving-aerial, and there they will produce 
electric oscillations similar to the ones at the 
transmitting-antenna. 

Telegraph signals are sent by the breaking 
up of the oscillations at the transmitting-station 
into long and short trains of oscillations corre- 
sponding to the dots and dashes of ordinary 
wire telegraphy. In other words, while . the 
sending-key is held down for a dash, there will 
be a long series of oscillations in the antenna, 
and for the dot a short series, and these short 
and long trains of waves will spread out to the 
receiving-aerial where they will reproduce the 
same series of oscillations. But only a small 
part of the energy will act on the receiving- 
aerial because the waves like those on the pond 
spread in all directions and grow rapidly 
weaker. Hence the advantage of an extremely 
delicate instrument like the audion to amplify 
the signals received. 

The oscillations used in wireless telegraphy 
these days are very rapid, usually entirely too 



190 INVENTIONS OF THE GREAT WAR 

rapid, to affect an ordinary telephone receiver, 
and if they did they would produce a note of 
such high pitch that it could not be heard. So 
it is customary to interrupt the oscillations, 
breaking them up into short trains of waves, 
and these successive trains produce a note of 
low enough pitch to be heard in the telephone 
receiver. Of course the interruptions are of 
such high frequency that in the sending of a dot- 
and-dash message each dot is made up of a great 
many of the short trains of waves. 

Now in radiotelephony it is not necessary to 
break up the oscillations, but they are allowed to 
run continuously at very high speed and act as 
carriers for other waves produced by speaking 
into the transmitter; that is, a single speech- 
wave would be made up of a large number 
of smaller waves. To make wireless tele- 
phony a success it was necessary to find some 
way of making perfectly uniform carrier-waves, 
and then of loading on them waves of speech. 
Of course, the latter are not sound-waves, be- 
cause they are not waves of air, but they are 
electro-magnetic waves corresponding exactly 
to the sound-waves of air and at the receiving- 
end they affect the telephone receiver in the 



TALKING IN THE SKY 191 

same way that it is affected by the electric 
waves which are sent over telephone wires. The 
telephone engineers found that the audion 
could he used to regulate the carrier-waves and 
also to superpose the speech-waves upon them, 
and -at the receiving-station the audion was used 
to pick up these waves, no matter how feeble 
they might be, and amplify them so that they 
could be heard in a telephone receiver. 

TALKING WITHOUT WIEES 

Attempts at long-distance talking without 
wires were made from Montauk Point, on the 
tip of Long Island, to Wilmington, Delaware, 
and they were successful. This was in 1915. 
The apparatus was still further improved and 
then the experiment was tried of talking from 
the big Arlington station near Washington to 
Darien, on the Isthmus of Panama. This was 
a distance of twenty-one hundred miles, and 
speech was actually transmitted through space 
over that great distance. That having proved 
successful, the next attempt was to talk from 
Arlington to Mare Island and San Diego, on the 
Pacific Coast, a distance of over twenty-five 
hundred miles. This proved a success, too, and 



192 INVENTIONS OF THE GREAT "WAR 

it was found possible even to talk as far as 
Honolulu. 

The engineers now felt confident that they 
could talk across the Atlantic to Europe, and 
so in October of 1915 arrangements were made 
to conduct experiments between Arlington and 
the Eiffel Tower in Paris. Although the war 
was at its height, and the French were strain- 
ing every effort to hold back the Germans at 
that time, and although there were constant de- 
mands for the use of radiatelegraphy, the 
French showed such an appreciation of science 
that they were willing to lend their aid to these 
experiments. The Eiffel Tower could be used 
only for short periods of time, and there was 
much interference from other high-powered 
stations. Nevertheless, the experiment proved 
perfectly successful, and conversation was car- 
ried on between our capital and that of France, 
a distance of thirty-six hundred miles. At the 
same time, an operator in Honolulu, forty-five 
hundred miles away, heard the messages, and 
so the voice at Arlington carried virtually one 
third of the way around the globe. After that 
achievement, there was a lull in the wireless- 
telephone experiments because of the war. 




(C) G. V. Buck 

Radio Head-gear of an Airman 




(C) G. V. Buck 

Carrying on Conversation by Radio with an Aviator 
Miles Away 



TALKING IN THE SKY 193 

But there soon came an opportunity to make 
very practical use of all the experimental work. 
As soon as there seemed to be a possibility that 
we might be drawn into the war, the Secretary 
of the Navy asked for the design of apparatus 
that would make it possible for ships to converse 
with one another and with shore stations. Of 
course all vessels are equipped with wireless- 
telegraph apparatus, but there is a decided ad- 
vantage in having the captain of one ship talk 
directly with the captain of another ship, or 
take his orders from headquarters, with an 
ordinary telephone receiver and transmitter. 
A special equipment was designed for battle- 
ships and on test it was found that ships could 
easily converse with one another over a distance 
of thirty-five miles and to shore stations from 
a distance of a hundred and seventy-five miles. 
The apparatus was so improved that nine con- 
versations could be carried on at the same time 
without any interference of one by the others. 

When it became certain that we should have 
to enter the war, there came a call for radio- 
telephone apparatus for submarine-chasers, and 
work was started on small, compact outfits for 
these little vessels. 



194 INVENTIONS OF THE GREAT WAR 

KADIOTELEPHONES FOE AIRPLANES 

Then there was a demand for radiotelephone 
apparatus to be used on airplanes. This was a 
much more complicated matter and called for a 
great deal of study. The way in which problem 
after problem arose and was solved makes an 
exceedingly interesting narrative. It seemed 
almost absurd to think that a delicate radio- 
telegraph apparatus could be made to work in 
the terrific noise and jarring of an airplane. 
The first task was to make the apparatus noise- 
proof. A special sound-proof room was con- 
structed in which a noise was produced exactly 
imitating that of the engine exhaust of an air- 
plane engine. In this room, various helmets 
were tried in order to see whether they would 
be proof against the noise, and finally a very 
suitable helmet was designed, in which the tele- 
phone receiver and transmitter were installed. 

By summer-time the work had proceeded so 
far that an airplane equipped with transmitting- 
apparatus could send spoken messages to an 
operator on the ground from a distance of two 
miles. The antenna of the airplane consisted 
of a wire with a weight on the lower end, which 



TALKING IN THE SKY 195 

hung down about one hundred yards from the 
body of the machine. But a trailing antenna 
was a nuisance in airplane manoeuvers, and it 
was also found that the helmet which was so 
satisfactory in the laboratory was not just the 
thing for actual service in an airplane. It had 
to fit very tightly around the ears and the 
mouth, and as the airplane went to high alti- 
tudes where the air-pressure was much lower 
than at the ground level, painful pressures were 
produced in the ears which were most annoy- 
ing. Aside from that, in actual warfare air- 
planes have to operate at extreme heights, 
where the air is so rare that oxygen must be 
supplied to the aviators, and it was difficult to 
provide this supply of oxygen with the radio 
helmet tightly strapped to the head of the op- 
erator. But after considerable experiment, this 
difficulty was overcome and also that of the 
varying pressures on the ears. 

Another great difficulty was to obtain a steady 
supply -of power on the airplane to operate the 
transmitting-apparatus. It has been the prac- 
tice to supply current on airplanes for wireless- 
telegraph apparatus by means of a small elec- 
tric generator which is revolved by a little pro- 



196 INVENTIONS OF THE GREAT WAR 

peller. The propeller in turn is revolved by 
the rush of air as it is carried along by the plane. 
But the speed of the airplane varies consider- 
ably. At times, it may be traveling at only 
forty miles per hour, and at other times as high 
as one hundred and sixty miles per hour, so 
that the little generator is subjected to great 
variations of speed and consequent variations 
of voltage. This made it impossible to produce 
the steady oscillations -that are required in wire- 
less telephony. After considerable experiment, 
a generator was produced with two windings, 
one of which operated through a vacuum tube, 
somewhat like an audion, and to resist the in- 
crease of voltage produced by the other winding. 
Then another trouble developed. The sparks 
produced by the magneto in the airplane motor 
set up electro-magnetic waves which seriously 
affected the receiving-instrument. There was 
no way of getting rid of the magneto, but the 
wires leading from it to the engine were in- 
cased in metal tubes which were grounded at 
frequent intervals, and in that way the trouble 
was overcome to a large extent. The magnetos 
themselves were also incased in such a wav that 



TALKING IN THE SKY 197 

electro-magnetic waves would not be radiated 
from them. 

Instead of using trailing wires which were 
liable to become entangled in the propeller, the 
antenna was extended from the upper plane to 
the tail of the machine, and later it was found 
that by using two short trailing antennae one 
from each tip of the wings, the very best results 
could be obtained. Still another development 
was to embed the antenna wires in the wings 
of the plane. 

It was considered necessary, if the apparatus 
was to be practicable, to be able to use it over 
a distance of two thousand yards, but in experi- 
ments conducted in October, 1917, a couple of 
airplanes were able to talk to each other when 
twenty-three miles apart, and conversations 
were carried on with the ground from a distance 
of forty-five miles. The conditions under which 
these distances were attained were unusual, and 
-a distance of three miles was accepted as a 
standard for communication between airplanes. 
The apparatus weighed only fifty-eight pounds 
and it was connected with both the pilot and the 
observer so that they could carry on conversa- 



198 INVENTIONS OF THE GREAT WAR 

tions with each other and could both hear 
the conversation with other airplanes or the 
ground. As a matter of fact, airplanes with 
standard apparatus are able to talk clearly to a 
distance of five miles and even to a distance of 
ten miles when conditions are favorable, and 
they can receive messages from the ground over 
almost any distance. 

A similar apparatus was constructed for sub- 
marine-chasers with a standard range of con- 
versation of over five miles. Apparatus was 
manufactured in large quantities in this country 
and all our submarine-chasers were equipped 
with it, as well as a great many of our airplanes 
and seaplanes, and we furnished radio-appa- 
ratus sets to our allies which proved of im- 
mense value in the war. This was particularly 
so in the case of submarine detection, when it 
was possible for a seaplane or a balloon to re- 
port its findings at once to submarine-chasers 
and destroyers, and to guide them in pursuit -of 
submarines. 

The improved audion holds out a wonder- 
ful future for radiotelephony. For receiving, 
at least, no elaborate aerial will be needed, and 
with a small loop of wire, an audion or two, 



TALKING IN THE SKY 199 

and simple tuning-apparatus any one can hear 
the radio gossip of the whole world. 

TELEGRAPHING TWELVE HUNDRED WORDS PER 
MINUTE 

Some remarkable advances were made in 
telegraphy also. During the war and since, 
messages have been sent direct from Washing- 
ton to all parts of the world. In the telegraph 
room operators are connected by wire with the 
different radio stations along the coast -and they 
can control the radio transmitters, sending their 
messages without any repeating at the radio 
stations. Long messages are copied off on a 
machine something like a type-writer, which, 
however, does not make type impressions, but 
cuts perforations in a long sheet of paper. The 
paper is then run through a transmitter at a 
high speed and the message is sent out at a rate 
of as much as twelve hundred words a minute. 
At the receiving-station, the message is received 
photographically on a strip of paper. The re- 
ceiving-instrument has a fine quartz thread in 
it, which carries a tiny mirror. A beam of light 
is reflected from the mirror upon the strip of 
sensitized paper. The radio waves twist the 



200 INVENTIONS OF THE GREAT WAR 

quartz thread ever so slightly, which makes the 
beam of light play back and forth, but of course 
the motion is greatly magnified. In this way 
a perfect record is made of the message in dots 
and dashes, which are translated into the corre- 
sponding letters of the alphabet. 

DETECTING EADIO SPIES 

There is another radio invention which we 
contributed during the war, that proved of ut- 
most service in thwarting German spies and 
which is going to prove equally valuable in time 
of pe'ace. Although a war invention, its peace- 
time service will be to save lives. It is a very 
simple matter to rig up a wireless-telegraph 
system that will send messages to a considerable 
distance, and simpler still to rig up a receiving- 
set. European governments have always dis- 
couraged amateur radiotelegraphy, but in this 
country restrictions used to be so slight that 
almost any one could set up and use a radio 
set, both for receiving and for transmitting. 
When we entered the war we were glad that 
amateurs had been encouraged to play with 
wireless, because we had hundreds of good radio 



TALKING IN THE SKY 201 

operators ready to work the sets which the army 
and the navy needed. 

But this was a disadvantage, too. Many 
operators were either Germans or pro-Germans 
and were only too willing to use their radio ex- 
perience in the interest of our enemies. It was 
a simple matter to obtain the necessary appa- 
ratus, because there was plenty of it to be had 
everywhere. They could send orders to fellow 
workers and receive messages from them, or 
they could listen to dispatches sent out by the 
government and glean information of great mili- 
tary and naval importance. The apparatus 
could easily be concealed: a wire hung inside 
a chimney, a water-pipe, even a brass bedstead 
could be used for the receiving-aerial. It wa-s 
highly important that these concealed stations 
be located, but how were they to be discovered? 

THE WIKELESS COMPASS 

This problem was solved very nicely. The 
audion had made it possible to receive radio 
signals on a very small aerial. In place of the 
ordinary stationary aerial a frame five feet 
square was set up so that it could be turned 



202 INVENTIONS OF THE GREAT WAR 

to any point of the compass. A few turns of 
copper-bronze wire were wound round it. This 
was called the "wireless compass." It was set 
up on the roof of the radio station and concealed 
within a cupola. The shaft on which it was 
mounted extended down into the operating- 
room and carried a wheel by which it could be 
turned. On the shaft was a circular band of 
aluminum engraved with the 360 degrees of the 
circle, and a couple of fixed pointers indicated 
true north and south. Now when a signal was 
received by the aerial, if it struck the frame 
edgewise the radio waves would reach one side 
before they would the other. Taking a single 
wave, as shown by the drawing, Fig. 11, we 
see that while the crest of the wave is sweep- 
ing over one side of the frame, the trough of the 
wave is passing the other side. Two currents 
are set up in the radio compass, one in the 
wires at the near side of the compass, and an- 
other in the wires at the far side of the com- 
pass. As these currents are of the same direc- 
tion, they oppose each other and tend to kill 
each other off, but one of the currents is 
stronger than the other because the crest of the 
wave is sweeping over that side, while the 




70$£T 



Courtesy of the "Scientific American" 

Fig. 11. The radio compass turned parallel to an oncoming 
electro-magnetic wave 



203 



204 INVENTIONS OF THE GREAT WAR 

trough of the wave is passing over the other. 
The length of the wave may be anything, but 
always one side will be stronger than the other, 
and a current equal in strength to the difference 
between the two currents goes down into the 
operating-room and affects the receiver. Now 
when the compass is set at right angles to the 
oncoming wave, both sides are affected simul- 
taneously and with the same strength, so that 
they kill each other off completely, and no 
current goes down to the receiver. Thus the 
strength of the signal received can be varied 
from a maximum, when the compass is parallel 
to the oncoming waves, to zero, when it is at 
right angles to them. 

To find out where a sending-station is, the 
compass is turned until the loudest sound is 
heard in the receiver and then the campass 
dial shows from what direction the signals are 
coming. At the same time, another line on the 
signals will be found by a second station with 
another compass. These directions are traced 
on a map; and where they meet, the sending- 
station must be located. 

With this apparatus it was possible to locate 
the direction of the station within a degree. 



TALKING IN THE SKY 205 

After the station had been located as closely 
as possible in this way, a mot or- truck was sent 
out in which there was a concealed radio com- 
pass. The truck would patrol the region 
located by the fixed compasses, and with it the 
position of the concealed station could be de- 
termined with perfect accuracy. The building 
would be raided and its occupants jailed and the 
radio equipment confiscated. 

Even receiving-sets were discovered with the 
portable compass, but to find them was a far 
more difficult task. For the receiving of mes- 
sages from distant points without a conspicuous 
aerial an audion would have to be used and this 
would set up feeble oscillations which could be 
picked up under favorable conditions by the 
portable compass. 

PILOTING SHIPS INTO POET 

And now for the peace-time application of all 
this. If the compass could be used to find those 
who tried to hide, why could it not also be used 
to find those who wished to be found? 

Every now and then a ship runs upon the 
rocks because it has lost its bearings in the fog. 
But there will be no excuse for such accidents 



206 INVENTIONS OF THE GREAT WAR 

now. A number of radio-compass stations have 
been located around the entrance and approach 
to New York Harbor. Similar stations have 
been, or soon will be, established at other ports. 
As soon as a ship arrives within fifty or a 
hundred miles of port she is required to call for 
her bearings. The operator of the control sta- 
tion instructs the ship to send her call letters 
for thirty seconds, and at the same time notifies 
each compass station to get a bearing on the 
ship. This each does, reporting back to the con- 
trol station. The bearings are plotted on a 
chart and inside of two minutes from the time 
the ship gives her call letters, her bearing is 
flashed to her by radio from the control station. 
The chart on which the plotting is done is 
covered with a sheet of glass. Holes are 
pierced through the glass at the location of each 
compass station. See Fig. 12. On the chart, 
around each station, there is a dial marked off 
in the 360 degrees of the circle. A thread 
passes through the chart and the hole in the 
glass at each station. These threads are at- 
tached to weights under the chart. When a 
compass station reports a bearing, the thread 
of that station is pulled out and extended across 




207 



208 INVENTIONS OF THE GREAT WAR 

the corresponding degree on the dial. The 
same is done as each station reports and where 
the threads cross, the ship must be located. 

Not only can the direction-finder be used to 
pilot a ship into a harbor, but it will also serve 
to prevent collisions at sea, because a ship 
equipped with a radio compass can tell whether 
another ship is coming directly toward her. 

And so as one of the happy outcomes of the 
dreadful war, we have an apparatus that will 
rob sea-fogs of their terrors to navigation. 



CHAPTER XI 

Warriors of the Paint-Brush 

WHEN the great European war broke out, 
it was very evident that the Entente 
Allies would have to exercise every resource 
to beat the foe which had been preparing for 
years to conquer the world. But who ever 
imagined that geologists would be called in -to 
choose the best places for boring mines under 
the enemy: that meteorologists would be sum- 
moned to forecast the weather and determine 
the best time to launch an offensive; that psy- 
cologists would be employed to pick out the men 
with the best nerves to man the machine-guns 
and pilot the battle-planes? Certainly no one 
guessed that artists and the makers of stage 
scenery would play an important part in the 
conflict. 

But the airplane filled the sky with eyes that 
at first made it impossible for an army to con- 
ceal its plans from the enemy. And then there 

209 



210 INVENTIONS OF THE GREAT WAR 

were eyes that swam in the sea — cruel eyes that 
belonged to deadly submarine monsters, eyes 
that could see without being seen, eyes that 
could pop up out of the water at unexpected 
moments, eyes that directed deadly missies at 
inoffensive merchantmen. They were cowardly 
eyes, too, which gave the ship no opportunity 
to strike back at the unseen enemy. A vessel's 
only safety lay in the chance that out in the 
broad reaches of the ocean it might pass beyond 
the range of those lurking eyes. It was a game 
of hide-and-seek in which the pursuer and not 
the pursued was hidden. Something had to be 
done to conceal the pursued as well, but in the 
open sea there was nothing to hide behind. 

HIDING IN PLAIN SIGHT 

There is such a thing as hiding in plain sight. 
You can look right at a tree-toad without see- 
ing him, because his colors blend perfectly with 
the tree to which he is clinging. You can watch 
a green leaf curl up and shrivel without realiz- 
ing that the curled edge is really a caterpillar, 
cunningly veined and colored to look just like 
a dying leaf; and out in the woods a speckled 
bird or striped animal will escape observation 



WARRIORS OF THE PAINT-BRUSH 211 

just because it matches the spotted light that 
comes through the underbrush. Nature is 
constantly protecting its helpless animals 
with colored coats that blend with the sur- 
roundings. 

Long ago clumsy attempts at concealment 
were made when war-vessels were given a coat 
of dark-gray paint which was supposed to make 
them invisible at a distance. Actually the 
paint made them more conspicuous; but, then, 
concealment did not count for very much be- 
fore the present war. 

It was the eyes of the submarines that 
brought a hurry call for the artists, and up to 
them was put the problem of hiding ships in 
plain sight. A new name was coined for these 
warriors of the paint-brush: camoufleurs they 
were called, and their work was known as 
camouflage. 

MATCHING THE SKY 

Of course, no paint will make a ship abso- 
lutely invisible at a short distance, but a large 
vessel may be made to disappear completely 
from view at a distance of six or seven miles 
if it is properly painted. 



212 INVENTIONS OF THE GREAT WAR 

To be invisible, a ship must reflect as much 
light and the same shade of light as do its sur- 
roundings. If it is seen against the background 
of the sea, it must be of a bluish or a greenish 
tint, but a submarine lies so low in the water 
that any object seen at a distance is silhouetted 
against the sky, and so the ship must have a 
coat of paint that will reflect the same colors 
as does the sky. Now, the sky may be of almost 
any color of the rainbow, depending upon the 
position of the sun and the amount of vapor or 
dust in the air. Fortunately in the North 
Sea and the waters about the British Isles, 
where most of the submarine attacks took place, 
the weather is hazy most of the time, and the 
ship had to be painted of such a color that it 
would reflect the same light as that reflected by 
a hazy sky. With a background of haze and 
more or less haze between the ship and the 
periscope of the U-boat, it was not a very diffi- 
cult matter to paint a ship so that it would be 
invisible six or seven miles away. One shade of 
gray was used to conceal a ship in the North 
Sea and an entirely different shade was used 
for the brighter skies of the Mediterranean. 

In this way, the artists made it possible for 



WARRIORS OF THE PAINT-BRUSH 213 

ships to sail in safety much nearer the pursuer 
who was trying to find them, and by just so much 
they reduced his powers of destruction. But 
still the odds were too heavy against the mer- 
chantman. Something must be done for him 
when he found himself within the seven-mile 
danger-zone. Here again the artists came to 
the rescue. 

Before merchant ships were armed, a sub- 
marine would not waste a torpedo on them, but 
would pound them into submission with shell. 
Even after ships were provided with guns, sub- 
marines mounted heavier guns and unless a 
ship was speedy enough to show a clean pair 
of heels, the pursuing U-boat would stand off 
out of range of the ship's guns and pour a 
deadly fire into it. But the ships, too, mounted 
larger guns and the submarines had to fall back 
upon their torpedoes. 

GETTING THE EANGE EOE THE TOEPEDO 

In order to fire its torpedo with any certainty, 
the U-boat had to get within a thousand yards 
of its victim. A torpedo travels at from 
thirty to forty miles per hour. It takes time 
for it to reach its target and a target which 



214 INVENTIONS OF THE GREAT WAR 

is moving at, say, fifteen knots, will travel 
live hundred yards while a thirty-knot tor- 
pedo is making one hundred yards. And so 
before the U-boat commander could discharge 
his torpedo, he had to know how fast the 
ship was traveling and how far away it was 
from him. He could not come to the surface 
and make deliberate observations, but had to 
stay under cover, not daring even to keep his 
eye out of water, for fear that the long wake 
of foam trailing behind -the periscope would 
give him away. All he could do, then, was 
to throw his periscope up for a momentary 
glimpse and make his calculations very quickly; 
then he could move to the position he figmred 
that he should occupy and shoot up his peri- 
scope for another glimpse to check up his calcu- 
lations. On the glass of this periscope, there 
were a number of graduations running verti- 
cally and horizontally. If he knew his victim 
and happened to know the height of its smoke- 
stacks or the length of the boat, he noted how 
many graduations they covered, and then by a 
set formula he could tell how far he was from 
the boat. At the same time he had to work out 
its rate of travel and note carefully the course 



WARRIOES OF THE PAINT-BRUSH 215 

it was holding before he could figure where 
his torpedo must be aimed. 

There was always more or less uncertainty 
about such observations, because they had to be 
taken hastily, and the camoufleurs were not slow 
to take advantage of this weakness. They in- 
creased the enemy's confusion by painting high 
bow- waves which made the ship look as if it were 
traveling at high speed. They painted the 
bow to look like the stern, and the stern to look 
like the bow, and the stacks were painted so that 
they appeared to slant in the opposite direc- 
tion, so that it would look as if the vessel were 
headed the other way. U-boats came to have a 
very wholesome respect for destroyers and 
would seldom attack a ship if one of these 
fast fighting-craft was about, and so destroyers 
were painted on the sides of ships as scare- 
crows to frighten off the enemy. 

MAKING STKAIGHT LINES LOOK CROOKED 

We say that "seeing is believing," but it is 
not very hard to deceive the eye. The lines in 
Fig. 13 look absolutely parallel, and they are; 
but cross-hatch the spaces between them, with 
the hatching reversed in alternate spaces, as in 



Fig. 13. Parallel lines that look straight 
Fig. 14. Parallel lines that do not look straight 



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Courtesy of the Submarine Defense Association 
Fig. 15. Letters that look all higgledy-piggledy, but are 
really straight 



216 



WARRIORS OF THE PAINT-BRUSH 217 

Fig. 14, and they no longer look straight. 
Take the letters on the left, Fig. 15. They 
look all higgledy-piggledy, but they are really 
straight and parallel, as one can prove by laying 
a straight-edge against them, or by drawing 
a straight line through each letter, as shown at 
the right, Fig. 16. Such illusions were used on 
ships. Stripes were painted on the hull that 
tapered slightly, from bow to stern, so that the 
vessel appeared to be headed off at an angle, 
when it was really broadside to the watcher at 
the other end of the periscope. 

There are color illusions, too, that were tried. 
If you draw a red chalk-mark and a blue one on 
a perfectly clean blackboard, the red line will 
seem to stand out and the blue one to sink into 
the black surface of the board, because your eye 
has to focus differently for the two colors, and 
a very dazzling effect can be had with alternat- 
ing squares of blue and red. Other colors give 
even more dazzling effects, and some of them, 
when viewed at a distance, will blend into the 
very shade of gray that will make a boat invisi- 
ble -at six miles. Y^hen U-boat commanders 
took observations on a ship painted with a 
" dazzle' ' camouflage, they saw a shimmering 



218 INVENTIONS OF THE GREAT WAR 

image which it was hard for them to measure on 
the fine graduations of their periscopes. Some 
ships were painted with heavy blotches of black 
and white, and the enemy making a hasty ob- 
servation would be apt to focus his attention 
on the dark masses and overlook the white parts. 
So he was likely to make a mistake in estimating 
the height of the smoke-stack or in measuring 
the apparent length of a vessel. 

A JOKE ON THE PHOTOGEAPHER 

Early in the submarine campaign one of our 
boats was given a coat of camouflage, and when 
the vessel sailed from its pier in the North 
River, New York, the owners sent a photog- 
rapher two or three piers down the river to 
photograph the ship as she went by. He took 
the picture, but when the negative was de- 
veloped, much to his astonishment he found 
that the boat was not all on the plate. In the 
finder of his camera, he had mistaken a heavy 
band of black paint for the stern of the ship, 
quite overlooking the real stern, which was 
painted a grayish white. The artist had fooled 
the photographer and at a distance of not m'ore 
than two or three hundred yards ! 



WARRIORS OF THE PAINT-BRUSH 219 

SEEING BEYOND THE HORIZON 

The periscope of a submarine that is running 
awash can be raised about fifteen feet above 
the water, which means that the horizon as 
viewed from that elevation is about six miles 
away, and if you draw a circle with a six- 
mile radius on the map of the Atlantic, you 
will find that it is a mere speck in the ocean; 
but a U-boat commander could see objects 
that lay far beyond his horizon because he was 
searching for objects which towered many feet 
above the water. The smoke-stacks of some 
vessels rise a hundred feet above the water- 
line, and the masts reach up to much greater 
altitudes. Aside from this, in the early days 
of the war steamers burned soft coal and their 
funnels belched forth huge columns of smoke 
which was visible from twenty to thirty miles 
away. 

When this was realized, efforts were made 
to cut down the superstructure of a ship as much 
as possible. Some vessels had their stacks 
cut down almost to the deck-line, and air-pumps 
were installed to furnish the draft necessary to 



220 INVENTIONS OF THE GREAT WAR 

keep their furnaces going. They had no masts 
except for slender iron pipes which could be 
folded down against the deck and could be 
erected at a moment's notice, to carry the 
aerials of the wireless system. Over the ship 
from stem to stern was stretched a cable, 
familiarly known as a ' ' clothes-line, ' ' upon 
which were laid strips of canvas that com- 
pletely covered the superstructure of the ship. 
These boats lay so low that they could not be 
seen at any great distance, and it was difficult 
for the U-boats to find them. They were slow 
boats; too slow to run away from a modern 
submarine, but because of their lowly structure, 
they managed to elude the German U-boats. 
When they were seen, the U-boat commanders 
were afraid of them. They were suspicious of 
anything that looked out of the ordinary, and 
preferred to let the "clothes-line ships" go. 

THE BKITISH MYSTEEY SHIPS 

The Germans had some very unhealthy ex- 
periences with the "Q-boats" or "mystery 
ships" of the British. These were vessels 
rigged up much like ordinary tramp steamers, 
but they were loaded with wood, so that they 



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WARRIORS OF THE PAINT-BRUSH 221 

would not sink, and their hatches were arranged 
to fall open at the touch of a button, exposing 
powerful guns. They also were equipped with 
torpedo-tubes, so that they could give the U-boat 
a dose of its own medicine. These ships would 
travel along the lanes frequented by submarines, 
and invite attack. They would limp along as 
if they had been injured by a storm or a U-boat 
attack, and looked like easy prey. When a sub- 
marine did attack them, they would send out 
frantic calls for help, and they had so-called 
' panic ' ' parties which took to the boats. Mean- 
time, a picked crew remained aboard, carefully 
concealed from view, and the captain kept his 
eye upon the enemy through a periscope dis- 
guised as a small ventilator, waiting for the 
U-boat to come within range of certain destruc- 
tion. Sometimes the panic party would lure 
the submarine into a favorable position by 
rowing under the stern as if to hide around the 
other side of the ship. At the proper moment, 
up would go the white ensign — the British 
man-of-war flag — the batteries would be un- 
masked, and a hail of shell would break loose 
over the Hun. Many a Grerman submarine was 
accounted for by such traps. 



222 INVENTIONS OF THE GREAT WAR 

Submarines themselves used all sorts of 
camouflage. They were frequently equipped 
with sails which they would raise to disguise 
themselves as peaceful sloops, and in this way 
they were able to steal up on a victim without 
discovery. Sometimes they would seize a ship 
and hide behind it in order to get near their 
prey. 

CAMOUFLAGE ON LAND 

But the call for the wielders of the paint- 
brush came not only from the sea. Their ser- 
vices were needed fully as much on land, and the 
making of land camouflage was far more in- 
teresting because it was more varied and more 
successful. Besides, it called for more than 
mere paint; all sorts of tricks with canvas, 
grass, and branches were used. Of course, the 
soldiers were garbed in dust-colored clothing 
and shiny armor was discarded. The helmets 
they wore were covered with a material that cast 
no gleam of light. In every respect, they tried 
to make themselves of the same shade as their 
surroundings. Like the Indians, they painted 
their faces. This was done when they made 
their raids at night. They painted their faces 



WARRIORS OF THE PAINT-BRUSH 223 

black so that they would not show the faintest 
reflection of light. 

A PAPER HORSE 

The most interesting camouflage work was 
done for the benefit of snipers or for observers 
at listening-posts close to the enemy trenches. 
It was very important to spy on the enemy and 
discover his plans, and so men were sent out 
as near his lines as possible, to listen to the con- 
versation and to note any signs of unusual ac- 
tivity which would be likely to precede a raid. 
These men were supplied with telephone wires 
which they dragged over No Man's Land, and 
by which they could communicate their dis- 
coveries to headquarters. Some very ingenious 
listening-posts were established. In one case 
a papier-mache duplicate of a dead horse was 
made, which was an exact facsimile of an ani- 
mal that had been shot and lay between the two 
lines. One night, the carcass of the horse was 
removed and the papier-mache replica took its 
place. In the latter a man was stationed with 
telephone connection back to his own lines. 
Here he had an excellent chance to watch the 
enemy. 



224 INVENTIONS OF THE GREAT WAR 

On another occasion a standing tree, whose 
branches had been shot away, was carefully 
photographed and an exact copy of it made, but 
with a chamber inside in which an observer could 
be concealed. One night while the noise of the 
workmen was drowned by heavy cannonading, 
this tree was removed and its facsimile was set 
up instead, and it remained for many a day be- 
fore the enemy discovered that it was a fake 
tree-trunk. It provided a tall observation post 
from which an observer could direct the fire of 
his own artillery. 

FOOLING THE WATCHEES IN THE SKY 

In the early stages of the war, it seemed im- 
possible to hide anything from the Germans. 
They had eyes everywhere and were able to an- 
ticipate everything the Allies did. But the 
spies that infested the sky were the worst handi- 
cap. Even when the Allies gained control of 
the air, the control was more or less nominal 
because every now and then an enemy observer 
would slip over or under the patrolling aero- 
planes and make photographs of the Allies ' 
lines. The photographs were carefully com- 



WARRIORS OF THE PAINT-BRUSH 225 

pared with others previously taken, that the 
slightest change in detail might be discovered. 
Airplane observers not only would be ready 
to drop bombs on any suspicious object or upon 
masses of troops moving along the roads, but 
would telephone back to their artillery to direct 
its fire upon these targets. Of course, the 
enemy knew where the roads were located and 
a careful watch was kept of them. 

The French did not try to hide the roads, but 
they concealed the traffic on the roads by hang- 
ing rows of curtains over them. As these cur- 
tains hung vertically and were spaced apart, one 
would suppose that they would furnish little 
concealment, but they prevented an observer 
in an aeroplane from looking down the length 
of a road. All the road he could see was that 
which lay directly under his machine, because 
there he could look between the curtains; if 
he looked obliquely at the road, the curtains 
would appear to overlap one another and would 
conceal operations going on under them. 

In one case, the Germans completely covered 
a sunken road with canvas painted to represent 
a road surface. Under this canvas canopy, 



226 INVENTIONS OF THE GREAT WAR 

troops were moved to an important strategic 
point without the slightest indication of such a 
movement. 

HIDING BIG GUNS 

Nature 's tricks of camouflage were freely used 
in the hiding of the implements of war on land. 
Our big guns were concealed by being painted 
with leopard spots and tiger stripes, the color 
and nature of the camouflage depending upon 
the station they were to occupy. In many cases, 
they were covered with branches of trees or 
with rope netting overspread with leaves. So 
careful was the observation of the air scouts 
that even the grass scorched by the fire of the 
gun had to be covered with green canvas to 
prevent betrayal of the position of the gun, 

KOADS THAT LED NOWHEEE 

In the making of an emplacement for a gun 
it was of the utmost importance that no fresh 
upturned earth be disclosed to the aerial ob- 
servers. Even foot-paths leading to it had to 
be concealed. Plans were carefully made to 
cover up all traces of the work before the work 
was begun. Where it was impossible to conceal 



WARRIORS OF THE PAINT-BRUSH 227 

the paths, they were purposely made to lead 
well beyond the point where the emplacement 
was building, and, still further to deceive the 
enemy, a show of work was sometimes under- 
taken at the end of the path. Wherever the 
sod had to be upturned, it was covered over 
with green canvas. The earth that was re- 
moved had to be concealed somewhere and the 
best place of concealment was found to be some 
old shell-hole which would hold a great deal 
of earth without any evidence that would be ap- 
parent to an observer in an aeroplane. If no 
shell-hole were handy, the excavated material 
had to be hauled for miles before a safe dump- 
ing-ground could be found. As far as possible 
everything was sunk below the earth level. 
Big pits were dug in which the mortars were 
placed, or if a shell-hole were empty, this was 
used instead. 

SHADOWLESS BUILDINGS 

Any projection above the ground was apt to 
cast a shadow which would show up on the ob- 
server's photographs. This was a difficulty 
that was experienced in building the hangars 
for airplanes. The roofs of these sheds were 



228 INVENTIONS OF THE GREAT WAR 

painted green so as to match the sod around 
them, but as they projected above their sur- 
roundings, they cast shadows which made them 
clearly evident to the enemy. This was over- 
come by the building of shadowless hangars; 
that is, hangars with roofs that extended all 
the way to the ground at such an angle that they 
would cause no shadow except when the sun was 
low. In some cases, aeroplanes were housed 
in underground hangars, the approach to which 
was concealed by a canvas covering. As for 
the machines themselves, they scorned the use 
of camouflage. Paint was little protection to 
them. Some attempt was made to use trans- 
parent wings of cellon, a material similar to 
celluloid, but this did not prove a success. 

THE PHOTOGRAPHIC EYE 

Although camoufleurs made perfect imitations 
of natural objects and surroundings, they were 
greatly concerned to find that the flying observ- 
ers could see through their disguises. To the 
naked eye the landscape would not show the 
slightest trace of any suspicious object, but by 
the use of a color-screen to cut out certain rays 
of light, a big difference would be shown between 



WARRIORS OF THE PAINT-BRUSH 229 

the real colors of nature and the artist's copies 
of them. For instance, if a roof painted to 
look like green grass were viewed through a 
red color-screen, it would look brown ; while the 
real grass, which apparently was of exactly the 
same shade as the roof, would look red. It 
had not been realized by the artists who had 
never studied the composition of light, that there 
is a great deal of red in the green light reflected 
by grass, and that if they were to duplicate 
this shade of green, they must put a certain 
amount of red paint in their imitation grass 
roofs. Air scouts did not depend upon their 
eyes alone, but used cameras so that they could 
study their photographs at their leisure and by 
fitting the cameras with different color-screens, 
they could analyze the camouflage and undo the 
patient work of the artist. 

A CALL FOE THE PHYSICIST 

To meet this situation, another man was sum- 
moned to help — the physicist, who looks upon 
color merely as waves of ether; who can pick 
a ray of light to pieces just as a chemist can 
analyze a lump of sugar. Under his expert 
guidance, colors of nature were imitated so that 



230 INVENTIONS OF THE GREAT WAR 

they would defy detection. Aside from this, the 
physicist helped to solve the tricks of the 
enemy's camoufleurs. 

But the physicist had barely rolled up his 
sleeves and got into the fray when the armis- 
tice was signed which put an end to the shams 
as well as to the realities of the great war. 
While the work of camouflage was not com- 
pleted, we owe an inestimable debt to the men 
who knew how to fake scenery and to their 
learned associates who count the wave lengths 
of light, and although their trade was a trade of 
deception and shams, there was no sham *about 
the service they rendered. 

MAKING SHIPS VISIBLE 

While in war safety lies in invisibility, in 
peace the reverse is true. Now that the war is 
over, it may seem that the work of the camou- 
fleurs can find no useful application; but it 
was impossible to learn how to make objects 
invisible without also learning how to make 
them conspicuously visible. As a consequence, 
we know now how to paint a ship so that it 
will show up more clearly in foggy weather, 
thereby reducing the danger of collision. We 



WARRIORS OF THE PAINT-BRUSH 231 

know, too, how to paint light-ships, buoys, etc., 
so that they will be much more conspicuous 
and better guides to mariners, and how to color 
railroad signals and road signs so that they 
will be more easily seen by locomotive engineers 
and automobile drivers. 



CHAPTEE XII 

Submarines 

IT was an American invention that dragged 
America into the war — an American inven- 
tion in the hands of barbarians and put to un- 
speakably barbarous use. 

After seeing how the Huns used the sub- 
marine we are not so sure that we can take much 
pride in its invention. But if any blame at- 
taches to us for developing the submarine, we 
made amends by the way in which we fought the 
German U-boat and put an end to German 
frightfulness on the sea. Of course, the credit 
for Germany's defeat is not for a moment 
claimed by Americans alone, but it must be ad- 
mitted that we played an important part in 
overcoming the menace of the U-boat. 

There is no question that the submarine was 
an American invention. To be sure, we can look 
into ancient books and find suggestions for navi- 
gating under the surface of the sea, but the 

232 



SUBMARINES 233 

first man who did actually build -a successful 
submarine was David Bushnell, back in the 
Revolutionary War. After him came Robert 
Fulton, who carried the invention farther. He 
built and operated a submarine for the French 
Government, and, in more recent years, the sub- 
marine became a practical vessel of war in the 
hands of John P. Holland and Simon Lake, 
both Americans. However, we are not inter- 
ested, just now, in the history of the submarine, 
but rather in the development of this craft 
during the recent war. 

With Great Britain as an enemy, Germany 
knew that she was hopelessly outclassed on the 
sea ; but while "Britannia ruled the waves," she 
did not rule the depths of the sea, and so Ger- 
many decided to claim this realm for her own. 
Little attention did she pay to surface vessels. 
Except in the Dogger Bank engagement and the 
Battle of Jutland, the German first-class ves- 
sels did not venture out upon the open sea, and 
even the lighter craft merely made occasional 
raids under cover of fog or darkness, only 
to cut and run as soon as the British vessels 
appeared. The submarine boat, or unter see- 
boot as the Germans called it, was virtually the 



234 INVENTIONS OF THE GREAT WAR 

only boat that dared go out into the high seas ; 
consequently, the Germans specialized upon 
that type of craft and under their close atten- 
tion it grew into a highly perfected war-vessel. 
But the Germans were not the only ones to de- 
velop the submarine, as we shall see. 

CONSTRUCTION OF THE U-BOATS 

When the great war broke out, the German U- 
boat was a comparatively small craft, less than 
150 feet long, with its main hull only 12 feet in 
diameter. It could make a speed of 12 knots on 
the surface and only 9 when submerged. But 
as the war progressed, it grew larger and 
larger, until it attained a length of over 300 
feet and its speed was increased to 12 knots 
when submerged and 18 knots on the surface. 

Figs. 16 to 18 show the construction of one 
of the early U-boats. The later boats were 
built after the same general plan, but on a 
bigger scale. 

It is not always safe to judge a thing by its 
name; to do so is apt to lead to sad mistakes. 
One would naturally suppose, from its name, 
that a submarine is a boat that lives under 
water, like a fish. But it is not a fish; it is 





235 



236 INVENTIONS OF THE GREAT WAR 

an air-breathing animal that prefers to stay 
on the surface, only occasionally diving under to 
hide from danger or to steal upon its prey. 
During the war, the German U-boats did not 
average three hours per day under the surface ! 
Because they were intended to run on the sur- 
face they had to be built in the form of a sur- 
face vessel, so as to throw off the waves and 
keep from rolling and pitching too much in a 
seaway. But they also had to be built to with- 
stand the crushing weight of deep water, and as 
a cylinder is much stronger than a structure of 
ordinary boat shape, the main hull was made cir- 
cular in section and of heavy plating, strongly 
framed, while around this was an outer hull 
of boat shape, as shown in Fig. 18. 

PUTTING HOLES IN A TANK TO KEEP IT FULL, 

The space between the inner and outer 
hulls was used for water ballast and for reser- 
voirs of oil to drive the engines; and, strange 
as it may seem, the oil-tanks were always kept 
full by means of holes in the bottom of them. 
As the oil was consumed by the engines, water 
would flow into the reservoir to take its place, 
and the oil, being lighter than water, would float 



r^ 



OUTER HULL- 



OUTEP MULL- 




OUTER 

WATE«- BALLAST 

TANK 



DETACHABLE KEEl/ 



Courtesy of the "Scientific American" 

Fig. 18. Transverse section through conning-tower, showing 
the interior (circular) pressure-resisting hull and the 
lighter exterior hull, which is open to the sea 



237 



238 INVENTIONS OF THE GREAT WAR 

on top. The false hull was of light metal, be- 
cause as it was open to the sea, the pressure on 
the inside was always the same as that on the 
outside. The reservoirs of oil and the water- 
ballast tanks protected the inner hull of the 
vessel from accidental damage and from hostile 
shell and bombs. There were water-ballast 
tanks inside the inner hull as well, as shown in 
the cross-sectional view, Fig. 18. The water 
in the ballast-tanks was blown out by com- 
pressed air to lighten the U-boat and the boat 
was kept on an even keel by the blowing out 
or the letting in of water in the forward and 
after tanks. 

A heavy lead keel was attached to the bottom 
of the boat, to keep it from rolling too much. 
In case of accident, if there were no other way of 
bringing the boat to the surface, this keel could 
be cast loose. 

At the forward end, where the torpedo-tubes 
were located, there was a torpedo-trimming 
tank. Torpedoes are heavy missiles and every 
time one was discharged the boat was lightened, 
and the balance of the submarine was upset. 
To make up for the loss of weight, water had 
to be let into the torpedo-trimming tank. 



SUBMARINES 239 

A submarine cannot float under-water 'With- 
out swimming ; in other words, it must keep its 
propellers going to avoid either sinking to the 
bottom of the sea or bobbing up to the surface. 
To be sure, it can make itself heavier or lighter 
by letting water into or blowing water out of 
its ballast-tanks, but it is impossible to regulate 
the water ballast so delicately that the sub- 
marine will float submerged; and should the 
boat sink to a depth of two hundred feet or so, 
the weight of water above it would be suffi- 
cient to crush the hull, so it is a case of sink 
or swim. Usually enough ballast is taken on 
to make the submarine only a little lighter than 
the water it displaces ; and then to remain under, 
the vessel must keep moving, with its hori- 
zontal rudders tilted to hold it down. The hori- 
zontal rudders or hydroplanes of the U-boat 
are shown in Fig. 17, both at the bow and at 
the stern. 

The main hull of the vessel was literally filled 
with machinery. In the after part of the boat 
were the Diesel oil-engines with which the 
U-boat was propelled when on the surface. 
There were two engines, each driving a pro- 
peller-shaft. It was impossible to use the en- 



240 INVENTIONS OF THE GREAT WAE 

gines when the vessel was submerged, not be- 
cause of the gases they produced — these could 
easily have been carried out of the boat — but 
because every internal-combustion engine con- 
sumes enormous quantities of air. In a few 
minutes the engines would devour all the air 
in the hull of the submarine and would then 
die of suffocation. And so the engines were 
used only when the submarine was running 
awash or on the surface, and then the air con- 
sumed by them would rush down the hatchway 
like a hurricane to supply their mighty lungs. 

E^GHSTES THAT BUEN HEAVY OIL 

The oil-engines were strictly a German in- 
vention. In the earlier days of the submarine 
gasolene-engines were used, but despite every 
precaution, gasolene vapors occasionally would 
leak out of the reservoirs and accumulate in 
pockets or along the floors of the hull, and it 
needed but a spark to produce an explosion 
that would blow up the submarine. But 
Eudolph Diesel, a German, invented an engine 
which would burn heavy oils. 

In the Diesel engine there are no spark-plugs 
and no magneto: the engine fires itself with- 




■ ' ■ \ ' 

n<\ !■;; 

.•■•.;•' 



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faC 



u -2 



■so 



-2 c 



SUBMARINES 241 

out electrical help. Air is let into the cylinder 
at ordinary atmospheric pressure, or fifteen 
pounds per square inch. But it is compressed 
by the upward stroke of the piston to about 
five hundred pounds per square inch. When 
air is compressed it develops heat and the sud- 
den high compression to over thirty times its 
normal pressure raises the temperature to some- 
thing like 1000 degrees Fahrenheit. Just as 
this temperature is reached, a jet of oil is blown 
into the cylinder by air under still higher pres- 
sure. Immediately the spray of oil bursts into 
flame and the hot gases of combustion drive the 
piston down. Because of the intense heat al- 
most any oil, from light gasolene to heavy, al- 
most tarlike oils, can be used. As heavy oils 
do not throw off any explosive vapors unless 
they are heated, they make a very safe fuel for 
submarines. 

To drive the U-boat when no air was to be had 
for the engines, electric motors were used. 
There was one on each propeller-shaft and the 
shafts could be disconnected from the oil-en- 
gines when the motors were driving. The mo- 
tors got their power from storage batteries in 
the stern of the submarine and under the floors 



242 INVENTIONS OF THE GREAT WAR 

forward. The motors when coupled to and 
driven by the engines generated current which 
was stored in the storage batteries. The sub- 
marine could not run on indefinitely under- 
water. When its batteries were exhausted it 
would have to come to the surface and run its 
engines to store up a fresh charge of electricity. 
The electric motors gave the boat a speed of 
about nine knots. 

In addition to the main engines and motors, 
there was a mass of auxiliary machinery. 
There were pumps for compressing air to blow 
the ballast-tanks and to discharge the torpedoes. 
There was a special mechanism for operating 
the rudder and hydroplanes, and all sorts of 
valves, indicators, speaking-tubes, signal lines, 
etc. The tiny hull was simply crammed with 
mechanism of all kinds and particularly in the 
early boats there was little room for the accom- 
modation of the officers and crew. The officers 1 
quarters were located amidships, and forward 
there were the folding berths of the crews. In 
the later boats more space was given the men. 
The large U-boats carried a crew of forty and 
as the hazards of submarine warfare increased, 
more attention had to be paid to the men. 



SUBMARINES 243 

FAT MEN NOT WANTED 

Oddly enough, small, slender men were pre- 
ferred for submarine duty, not because of lack 
of space, but because it was apt to be very cold 
in a submarine, particularly in the winter-time. 
The water cooled off the boat when the sub- 
marine was traveling submerged, and the motors 
gave off little heat; while when the vessel was 
running on the surface the rush of wind to sup- 
ply the engines kept the thermometer low. This 
meant that the men had to pile on much clothing 
to keep warm, which made them very bulky. 
The hatchway was none too large and a fat man, 
were he bundled up with enough clothing to keep 
him warm, would have a hard time squeezing 
through. 

In the center of the vessel was the main hatch- 
way, leading up to the conning-tower, which 
was large enough to hold from three to five men. 
This was the navigating-room when the vessel 
was running submerged, and above it was the 
navigating-b ridge, used when the -submarine 
was on the surface. In the conning-tower there 
was a gyroscopic compass ; a magnetic compass 
would not work at all inside the .steel hull of 



244 INVENTIONS OF THE GREAT WAR 

the U-boat. And here were .the periscopes or 
eyes of the submarine, rising from fifteen to 
twenty feet above the roof of the conning- 
tower. There were usually two periscopes. 
They could be turned around to give the 
man at the wheel a view in any direction and 
they were used sometimes even when the vessel 
was running on the surface, to give a longer 
range of vision. 

THE BLINDNESS OF THE SUBMAEINE 

Now, a submarine cannot see anything under- 
water. The commander cannot even see the 
bow of his boat from the conning-tower, and 
until he gets near enough to the surface to 
poke his periscope out of water he is absolutely 
blind and must feel his way about with compass 
and depth-gage. It was always an anxious mo- 
ment for the U-boat commander, when he was 
coming up, until his periscope broke out of the 
water and he could get his bearings ; and even 
that was attended with danger, for his peri- 
scope might be seen. Of course a periscope 
is a very insignificant object on the broad sea, 
but when a submarine is moving its periscope 
is followed by a wake which is very conspic- 



SUBMARINES 245 

uous, and so the U-boat ran a chance of being 
discovered and destroyed before it could dive 
again to a safe depth. Later, telescoping peri- 
scopes were used, which could be raised by 
means of a hand-lever. The submarine would 
run along just under the surface and every 
now and then it would suddenly raise its peri- 
scope for an observation and drop it down again 
under cover if there was danger nigh. This 
was much simpler and quicker than having a six- 
or eight-hundred-ton boat -come up to the sur- 
face and dive to safety. Pie might even collide 
with a vessel floating on the surface, but- to 
lessen this danger submarines were furnished 
with ears or big microphone diaphragms at each 
side of the hull by which a ship could be located 
by the noise of its propellers. 

In the bow were the torpedo-tubes and the 
magazine of torpedoes. At first there were only 
two torpedo-tubes, but later the number was 
increased to four. These were kept constantly 
loaded, so that the projectiles could be launched 
in rapid succession, if necessary, without a 
p'ause for the insertion of a fresh torpedo. In 
some submarines tubes were provided in the 
stern also so that the boat could discharge a 



246 INVENTIONS OF THE GREAT WAE 

torpedo at its enemy while running away from 
him. 

Each tube was closed at the outer end by a 
cap and at the inside end by a breech-block. 
The tube was blown clear of water by means of 
compressed air, and of course the outer cap was 
closed when the breech was open to let in a tor- 
pedo. Then the breech was closed, the, cap 
opened, and the torpedo was discharged from 
the tube by a blast of air. 

THE TORPEDO 

A torpedo is really a motor-boat, a won- 
derfully constructed boat, fitted with an en- 
gine of its own that is driven by compressed 
air and which drives the torpedo through the 
water at about forty miles per hour. The 
motor-boat is shaped like a cigar and that 
used by the Germans was about fifteen feet 
long and fourteen inches in diameter. We 
used much larger torpedoes, some of them 
being twenty-two feet long. Ours have a large 
compressed-air reservoir and will travel for 
miles; but the Germans used their torpedoes 
at short ranges of a thousand yards and under, 
cutting down the air-reservoir as much as pos- 



SUBMARINES 247 

sible and loading the torpedo with an extra 
large explosive charge. 

We found in the Diesel engine that when 
air is highly compressed it becomes very 
hot. When compressed air is expanded, the 
reverse takes place, the air becomes very cold. 
The air that drives the motor of the torpedo 
grows so cold that were no precautions taken 
it would freeze any moisture that might be 
present and would choke up the engine with the 
frost. And so an alcohol flame is used to heat 
the air. The air-motor is started automatically 
by release of a trigger as the torpedo is blown 
out of the torpedo-tube. By means of gear- 
ing, the motor drives two propellers. These run 
in opposite directions, so as to balance each 
other and prevent any tendency for the torpedo 
to swerve from its course. The torpedo is 
steered by a rudder which is controlled by a 
gyroscope, and it is kept at the proper depth 
under water by diving-rudders which are con- 
trolled by a very sensitive valve worked by the 
weight of the water above it. The deeper the 
water, the greater the weight or pressure ; and 
the valve is so arranged that, should the tor- 
pedo run too far under, the pressure will cause 



248 INVENTIONS OF THE GREAT WAR 

the diving-rudders to tilt until the torpedo comes 
up again ; then if the torpedo rises too high, the 
valve will feel the reduction of pressure and 
turn the rudders in the other direction. 

The business end of a torpedo is a "war- 
head " packed with about four hundred 
pounds of TNT. At the nose of the tor- 
pedo is a firing-pin, with which the war-head 
is exploded. Ordinarily, the firing-pin does 
not project from the torpedo, but there is a 
little propeller at the forward end which is 
turned by the rush of water as the torpedo 
is driven on its course. This draws out the 
firing-pin and gets everything ready for the 
TNT to explode as soon as the firing-pin is 
struck. But the firing-pin is not the only means 
of exploding the torpedo. Inside there is a very 
delicate mechanism that will set off the charge 
at the least provocation. In one type of tor- 
pedo a steel ball is provided which rests in a 
shallow depression and the slightest shock, the 
sudden stopping or even a sudden swerve of the 
torpedo, would dislodge the ball and set off the 
charge. Hence various schemes, proposed by 
inventors, for deflecting a torpedo without 
touching the firing pin, would have been of no 
value at all. 



SUBMARINES 249 

GUNS ON SUBMARINES 

As torpedoes are expensive things, the 
U-boats were supplied with other means of 
destroying their victims. The Germans sprang 
a surprise by mounting guns on the decks of 
their submarines. At first these were arranged 
to be lowered into a hatch when the boat was 
running submerged, but later they were per- 
manently mounted on the decks so that they 
would be ready for instant use. They were 
heavily coated with grease and the bore was 
swabbed out immediately when the boat came to 
the surface, so that there was no danger of 
serious rust and corrosion. The 3-inch gun of 
the early months of the war soon gave way to 
heavier pieces and the latest U-boats were sup- 
plied with guns of almost 6-inch caliber and 
there was a gun on the after deck as well as 
forward. 

The U-boats depended upon radiotelegraphy 
to get their orders and although they did not 
have a very wide sending-range, they could re- 
ceive messages from the powerful German sta- 
tion near Berlin. The masts which carried the 
radio aerials could be folded down into pockets 



250 INVENTIONS OF THE GREAT WAR 

in the deck. From stem to stern over the entire 
boat a cable was stretched which was intended to 
permit the U-boat to slide under nets protect- 
ing harbor entrances, and in later boats -there 
were keen-toothed knives at the bow which 
would cut through a steel net. During the war 
German and Austrian U-boats occupied so much 
attention that the public did not realize the 
part that the Entente Allies were playing under 
the sea. America, Great Britain, France, and 
Italy made good use of submarines, operating 
them against enemy vessels, blockading enemy 
ports, and actually fighting enemy submarines. 

A STEAM-DRIVEN" SUBMARINE 

The British in particular did splendid work 
with the submarine and developed boats that 
were superior to anything turned out by the 
Germans. For instance, they developed a sub- 
marine which is virtually a submersible de- 
stroyer. It is 340 feet long and it can make a 
speed of 24 knots on the surface. The most 
remarkable part of this boat is that its engines 
are driven by steam. Its boilers are fired with 
oil fuel. There are two smoke-stacks which fold 
down when it submerges. Of course when run- 



SUBMARINES 251 

ning under-water the vessel is driven by elec- 
tricity and it makes a speed of 10 knots. It 
carries three 4-inch guns, two forward and one 
aft, and its displacement submerged is 2700 tons 
as against 800 tons for the largest German sub- 
marines. 

A SUBMAKINE THAT MOUNTS A TWELVE-INCH 
GUN 

Still more remarkable is the big " super-sub- 
marine' ' designed by the British to bombard the 
forts of the Dardanelles, but unfortunately it 
was built too late to be used there. This sub- 
marine carries a gun big enough for a battle- 
ship. It is of 12-inch caliber and weighs 50 
tons. Of course a big gun like that could not 
be fired athwart the submarine. It might bowl 
the little vessel over, even though it was a 
1700-ton submarine. The gun is mounted to 
fire fore and aft, with a deviation of only a few 
degrees to one side or the other, so that the 
shock of the recoil is taken by the length in- 
stead of the beam of the submarine. It fires a 
shell weighing 620 pounds and a full charge is 
not used, so that the extreme range is only 
about 15,000 yards. This submarine monitor 



252 INVENTIONS OF THE GREAT WAE 

would have been a very difficult target for the 
Turkish gunners to hit. 

When the war came to an end and the Ger- 
man submarines surrendered to the Entente 
Allies at Harwich, there was considerable 
public curiosity as to whether or not an exami- 
nation of the U-boats would disclose any 
wonderful secrets. But they contained nothing 
that the Allies did not already know, and one 
British officer stated that the plans of the Ger- 
man submarines had often fallen into their 
hands long before a U-boat of the same type 
was captured! 



CHAPTEB Xm 

Getting the Best of the U-Boat 

THE U-boat commander who sallied forth 
from the harbor of Wilhelmshaven in the 
early days of the war had nothing to fear. He 
was out to murder, not to fight. His prey was 
always out in the open, while he could kill with- 
out exposing more than his eye above water. 
Not even a sporting chance was allowed his 
victims, particularly when he chose unarmed 
merchantmen for his targets. He could come 
up boldly to the surface and shell a ship into 
submission. This was cheaper than torpedo- 
ing the vessel, because torpedoes are expensive. 
If the ship were speedy it might run away; or 
if the U-boat came up too close to its intended 
prey, the latter might run it down. That hap- 
pened occasionally and it was the only danger 
that the Herr Kommandcmt had to fear. 

If a destroyer suddenly appeared, the U-boat 
could dive into the shelter of the sea. If the 

253 



254 INVENTIONS OF THE GREAT WAR 

water were not too deep, it could lie on the 
bottom for two or more days if need be. There 
was plenty of air in the hull to sustain life 
for many hours and then the compressed air 
used for blowing the ballast-tanks could be 
drawn upon. In the U-boat there were potash 
cartridges to take up the carbon-dioxide, and 
tanks of pure oxygen to revitalize the air. If 
the submarine were damaged, it was not neces- 
sary for it to come to the surface to effect re- 
pairs. There were air-locks through which a 
diver could be let out of the boat. He was 
fitted with oxygen and potash cartridges, so 
that he did not need to be connected by an air- 
hose with the boat, but could walk around it 
freely to mend injured rudders or to clear the 
propeller of entanglements. 

Even the small submarines of those early 
days were capable of taking long voyages. 
Setting his course at a comfortable pace of 10 
knots, the U-boat commander could count on 
enough fuel to carry him 1600 miles, and if 
need be he could slow down to 8 knots and by 
using certain of his water-ballast tanks for 
additional oil-reservoirs, extend his cruising- 
radius to nearly 3000 miles. The big 800-ton 



GETTING THE BEST OF THE U-BOAT 255 

U-boats that were built later had a radius of 
5000 miles at an 8-knot speed. And so when 
the British closed the English Channel with 
nets and mines, Herr Kommandant was not at 
all perturbed; he could sail around the British 
Isles if he chose and make war upon trans- 
atlantic shipping. When harbors were walled 
off with nets, he could remain outside and sink 
vessels that were leaving or entering them. 

SUBMAEINE-CHASERS 

A real menace came when the U-boat com- 
mander popped his periscope out of the sea 
and saw several little motor-boats bearing down 
upon him. They seemed harmless enough, but 
a moment 's inspection showed them to be armed 
with guns fully as powerful as those he carried. 
It was useless to discharge a torpedo at so 
speedy and small a foe. A torpedo has to have 
a fairly deep covering of water, else its course 
will be disturbed by surface waves; and the 
submarine-chasers drew so little water that a 
torpedo would pass harmlessly under them. 
It was useless for the U-boat commander to 
come up and fight them with his guns. They 
would have been upon him before he could do 



256 INVENTIONS OF THE GREAT WAR 

that, and their speed and diminutive size made 
them very difficult targets to hit. Besides, he 
dared not risk a duel of shell, for he knew that 
if the precious inner hull of his boat were 
punctured, he could not seek refuge under 
water; and if he could not hide, he was lost. 
The little armed mosquito craft swarmed about 
the harbor entrances, ready to dash at any sub- 
marine that showed itself. They could travel 
twice as fast as the submarine when it was sub- 
merged and half again as fast as when it was 
running on the surface. 

Submarines had to take to cover when these 
chasers were about. Herr Kommandant did 
not even dare to take a look around through 
his periscope, because the streak of foam that 
trailed in its wake would betray him and im- 
mediately the speedy motor-boats would take 
up the chase ; and they had a disagreeable way 
of dropping bombs which, even if they did not 
sink the submarine, might produce such a con- 
cussion as to spring its seams. His foes had 
discovered one of his most serious defects. He 
was blind under-water and they were making 
the most of this handicap. 

Groping along under-water by dead-reckon- 



li 



I 1 ft%- % 




GETTING THE BEST OF THE U-BOAT 257 

ing was not any too safe a procedure near land, 
because he was liable at any moment to crash 
into an uncharted rock or maybe into the wreck 
of some submarine victim. He could not cor- 
rect his bearings without coming to the surface, 
and, in the black depths of the sea, a slight mis- 
calculation might send him to his doom. As 
was explained in the previous chapter, he had 
to keep moving, because he could not remain 
suspended under water. 

He was more helpless than a ship sailing 
in the densest of fogs. A ship can stop and 
listen to sound-signals, or even to the beat- 
ing of the surf on the shore, or it can take 
soundings to locate its position; and yet it is 
no uncommon occurrence for a ship to run 
ashore in a fog. How much easier it is for a 
submarine to lose its bearings when obliged to 
travel by dead-reckoning, particularly in the 
disconcerting excitement of the chase! To 
avoid the danger of collision with surface ves- 
sels, the commander chose to run at a depth of 
sixty-five feet. That wa's the upper limit of his 
safety-zone. A depth of «over two hundred feet 
was his lower limit, because, as stated before, 
the water-pressure at that depth would crush in 



258 INVENTIONS OF THE GREAT WAR 

his hull or at least start its seams. If the bot- 
tom were smooth and sandy, and not too deep, 
he could settle gently upon it and wait for dark- 
ness, to make his escape. 

But while he lay on a sandy bottom, he was 
still in danger. Trawlers were sweeping the 
bottom with nets. He might be discovered; 
and then if he did not come up and surrender, 
a bomb would let in the sea upon him. 

A HINT FROM NATURE 

While he could not see under water, his ad- 
versaries could. They had taken a hint from 
nature. The fish-hawk has no difficulty in spy- 
ing his submarine prey. Flying high above the 
water, he can see his victims at a considerable 
depth, and wait his chance to pounce upon an 
unwary fish that comes too near the surface. 
It is said that the British trained sea-gulls to 
hunt submarines. Sea-gulls will follow a ship 
far out to sea for the sake of feeding on refuse 
that is thrown, overboard. British submarines 
encouraged the birds to follow them, by throw- 
ing out bait whenever they came to the surface. 
Of course the birds could see the submarine 
even when it was submerged, and if they pur- 



GETTING THE BEST OF THE U-BOAT 259 

sued it, they were always rewarded with plenty 
of food. The gulls drew no fine distinction 
between Hun and Briton, and so it came that 
Herr Kommandant often groped his way along 
in the dark sea, totally oblivious of the fact that 
he was attended by an escort of feathered folk 
who kept the British chasers informed of his 
presence. 

In this connection it is interesting to note 
that the British trained sea lions to hunt sub- 
marines. The animals were taught at first to 
swim to a friendly submarine, locating it by 
the sound of its propellers. They were always 
rewarded with fish. These sea lions were muz- 
zled so that they could not go fishing on their 
own account. Then they learned to locate 
enemy submarines and pointed them out by 
swimming directly toward them and diving 
down to them. 

But there were human eyes, as well, that spied 
upon the U-boat. Fast seaplanes patrolled the 
waters, searching constantly for any trace of 
submarine. Its form could be vaguely outlined 
to a depth of from fifty to seventy-five feet, 
unless the sea were choppy, and once it was dis- 
covered, chasers or trawlers were signaled to 



260 INVENTIONS OP THE GREAT WAR 

destroy it with bombs or to entangle it in nets. 
Often a submarine would be discovered by a 
leak in its oil-tank which would leave a tell- 
tale trail. Sometimes when the U-boat itself 
could not be discerned, there would be slight 
shimmer, such as may be seen above a hot stove, 
caused by refraction of light in its wake. This 
was easily recognized by trained observers. 

Even better aerial patrols were the small 
dirigibles known as Blimps. They are a cross 
between a balloon and an airplane, for they 
have the body and the power-plant of an air- 
plane, but the planes are replaced by a gas- 
bag. Blimps could cruise leisurely and search 
the sea thoroughly. They could stop and hover 
directly over a submarine and drop explosives 
upon it with great accuracy. And so Herr 
Kommandant could take no comfort in hiding 
under a blanket of waves unless the blanket were 
so thick as to conceal his form completely from 
the eyes overhead. This made it imperative 
to leave the shallower waters near shore and 
push out into the deep sea, where the small 
chasers could not pursue him. But he could 
not shake of? his pursuers. Stream-trawlers 






SM 



Courtesy of "Scientific American " 

Airplane Stunning a U-boat with a Depth-bomb 



■:'■ 



GETTING THE BEST OF THE U-BOAT 261 

are built to ride the heaviest gales and they 
took up the chase out into the ocean. 

There was a decided advantage for the U- 
boat in moving out to sea. It had a wider 
field of activity and could more easily escape 
from its pursuers. But on the other hand, its 
prey also had an advantage. Out in the open 
ocean they were not obliged to follow the usual 
ship lanes and it was more difficult for a sub- 
marine to intercept them. There it took more 
U-boats to blockade a given area. 

A GAME OF HIDE-AND-SEEK 

Then, it ceased to be quite so one-sided a 
game when merchantmen began to carry guns. 
That made it necessary for the submarine com- 
mander to creep up on his victims stealthily, 
and depend upon his torpedoes. He had to 
get within a thousand yards of the ship and 
preferably within five hundred yards, in order 
to be sure of hitting it. If the ship could travel 
faster than he could, he had to do this without 
betraying his presence. But ship-captains 
soon learned that their safety lay in zig-zagging. 
When Herr Kommandant reached the point 



262 INVENTIONS OF THE GREAT WAR 

from which he had planned to attack, he would 
raise his telescopic periscope out of the water, 
expecting to see his victim within good torpedo 
range, only to find it sailing safely on another 
tack. Again, he wonld have to take observa- 
tions and make another try, probably with no 
better luck. It was a game of hide-and-seek 
in which the merchant ship had a good chance 
of making its escape, particularly when blotches 
of camouflage paint made it difficult for him to 
get the range, as described in Chapter XI. 

Slower ships could be attacked without all 
this maneuvering, provided the submarine's 
guns outranged those of the ship. And so U- 
boats were provided with larger and larger 
guns, which made it possible for them to stand 
off and pound the merchantmen while out of 
reach of the vessel's guns. But ships found a 
way of hiding on the surface of the sea. A 
vessel would spout forth volumes of dense black 
smoke which would obliterate it from view. 
(See Fig. 19.) If the wind was quartering, 
the ship would change its course and dodge be- 
hind the sheltering pall of smoke. Not only 
was the smoke produced on the vessel itself, 
but smoke-boxes were cast overboard to form 



GETTING THE BEST OF THE U-BOAT 263 

a screen behind the vessel. These smoke- 
boxes contained a mixture of coal-tar and phos- 
phorus and other chemicals which would pro- 
duce incomplete combustion. They were ig- 



— 




Courtesy of the Submarine Defense Association 

Fig. 19. How a ship hid behind smoke produced on its own 
stern, with different directions of wind 



nited by the rubbing of a phosphorus compound 
on a priming-composition, and then cast adrift 
to pour out dense volumes of heavy smoke. 
(See Fig. 20.) Behind this screen, the ship 
could dodge and zig-zag and if her speed were 



264 INVENTIONS OF THE GREAT WAR 

greater than that of the submarine, her chances 
of escape were very good. 

Another annoyance that Herr Kommandant 
experienced was, when he lifted his periscopio 




ueae*A0T ship 



suott aoi» 





fuo*t eiaua 



i.VO/U ZlOVO. 



Courtesy of the Submarine Defense Association 

EiG. 20. How a ship hid behind a screen of smoke produced 
by throwing smoke boxes overboard 



eye above water, to find it so smeared with a 
sticky substance that he could not see. His 
foes had strewn the water with tar-oil that had 
spread in a thin film over a surface miles in 
extent. This blinded him at first, but before 



GETTING THE BEST OF THE U-BOAT 265 

long he was equipped with a jet for washing off 
the periscope glass and that little annoyance 
was overcome. 

But the craft most dreaded by the U-boat 
commander were the destroyers. These light, 
high-powered, heavily armed vessels could 
travel twice as fast as he could on the surface 
and three times as fast as he could submerged. 
Shells were invented which would not ricochet 
from the surface of the sea, but would plow 
right through the water, where they struck and 
hit the submarine below water-level. 



However, it was not shell-fire that he dreaded, 
but the big "ash cans' ' loaded with TNT 
which were timed to explode far under water, 
and which would crush his boat or start its 
seams. It was not necessary for these bombs 
to hit the U-boat. When they went off they 
would send out a wave of pressure that would 
crush the boat or start its seams even if it were 
a hundred feet and more from the point of the 
explosion. Within limits, the deeper the explo- 
sion the wider would its destructive area be. 

The timing-mechanism of some depth bombs 



266 INVENTIONS OF THE GREAT WAR 

consisted merely -of a float on the end of a cord. 
When the bomb was thrown overboard this 
float remained on the snrface until the cord 
was pulled out to its full length, when there 
would be a yank on the firing-trigger and the 
charge would explode. In other depth bombs 
there was a valve operated by the pressure of 
the water. When the bomb sank to the depth 
for which the valve was set, the pressure of the 
water would force the valve in, exploding a 
cartridge which set off the charge. So power- 
ful were these depth bombs that the destroyer 
had to travel at high speed to get out of range 
of the explosion. 

Depth bombs were rolled off the stern of the 
destroyer and also thrown out from the sides 
of the vessel by means of mortars. Some of 
the mortars were Y-shaped and held a depth 
bomb in each arm of the Y. When a blank 3- 
inch shell was exploded at the base of the gun, 
both bombs would be hurled from the ship, one 
to port and the other to starboard. In this way 
the destroyer could drop the bombs in a "pat- 
tern" of wide area. Herr Kommandant gained 
a wholesome respect for these terriers of the 
sea. It was suicide to show himself anywhere 



GETTING THE BEST OF THE U-BOAT 267 

near a destroyer. In a moment the speedy boat 
would be upon him, sowing depth bombs along 
his course. His chances of escaping through 
this hail of high explosives were remote in- 
deed. 

The ships that he was most eager to destroy 
were either too speedy for him to catch, unless 
they happened to come his way, or else they 
were herded in large convoys protected by these 
dreaded destroyers. The convoy proved a most 
baffling problem for Herr Kommandant. He 
dared not attack the convoy by daylight. In a 
fog he might take a chance at picking off one 
of the ships, but even that was very risky. He 
could trail the convoy until dusk and then under 
cover of darkness draw near enough to dis- 
charge a torpedo, but in the daytime he must 
keep his distance because there were eyes in the 
sky watching for him. At the van and rear of 
the convoy there were kite balloons high in the 
sky, with observers constantly watching for 
periscopes, and for U-boats that might be lurk- 
ing under the surface. 

As the destroyers gained in experience, the 
difficulties of the U-boat attack grew greater 
and its work grew more and more perilous. 



268 INVENTIONS OF THE GREAT WAR 

The crew grumbled and grew mutinous. The 
morale of the men was shaken. We can 
imagine the horror of plunging hurriedly into 
the depths of the sea, and rushing along blindly 
under the surface, dodging this way and that, 
while terrific explosions of depth bombs stagger 
the submarine and threaten to crush it, and 
there is the constant expectation that the next 
explosion will tear the thin shell of the U-boat 
and let in the black hungry water. The tables 
were turned. Now, if never before, Herr Kom- 
mandant, the hunter, knew what it felt like to 
be hunted. 

It takes an exceptional man to go through 
such a harrowing experience with unshattered 
nerves. On at least one occasion, a submarine 
that was being depth-bombed came suddenly to 
the surface. The hatch flew open and the crew 
rushed out, holding up their hands and crying, 
"Kamerad." The U-boat was uninjured, but 
the shock of a depth-bomb explosion had put 
the electric-lighting system out of commission, 
and the crew, unnerved by the explosion and ter- 
rified by the darkness, had overpowered their 
officers and brought the boat to the surface. 




(C) Underwood & Underwood 

The False Hatch of a Mystery Ship and — 




The same Hatch opened to disclose the 3-Inch Gun and Crew 



GETTING THE BEST OF THE U-BOAT 269 

EYES IN" THE SEA 

There were other craft that Herr Komman- 
dcmt had to look out for. His were not the only 
submarines in the sea. His foes also were 
possessed of submarines. They could not see 
under water any better than he could, but they 
could fight on the surface as well as he, and 
they could creep up on him even as he crept 
up on his prey. As a French submarine com- 
mander puts it: "The U-boats used to enjoy 
the advantage of remaining themselves invisible 
while all the surface and aerial craft which were 
sent in pursuit of them were boldly outlined 
against the sky and visible to them. This is 
one of the reasons we used submarines to am- 
bush U-boats." Submarines were also used to 
accompany the convoys, so that the U-boat com- 
mander had to watch not only for the eyes 
of the ship's lookouts and the eyes in the kite 
balloons, but also for the periscope eyes that 
swam in the sea. 

TRAILING U-BOATS BY SOUND 

The troubles of the submarine-commander 
were multiplying. All over the world inventors 



270 INVENTIONS OF THE GREAT WAR 

were plotting his destruction. As long as we 
depended upon our eyes to ferret him out, the 
sea was a safe refuge, provided he dived deep 
enough, but when we began to use our ears as 
well, he found himself in a very serious predica- 
ment. Although light is badly broken up in its 
passage through water, sound-waves will travel 
through water much better than in air. The 
first listening-devices used were crude affairs 
and did not amount to much, particularly when 
the U-boats muffled their motors and engines 
so that they were virtually noiseless. But the 
French invented a very sensitive sound-de- 
tector. ' It consisted of a lot of tiny diaphragms 
set in a big hemisphere. There were two of 
these hemispheres, one at each side of the boat. 
When sound-waves struck these hemispheres, 
the diaphragms would respond. At the focus 
of each hemisphere there was a megaphone re- 
ceiver; one of these carried the sound to the 
operator's right ear and the other to his left. 
He would turn a megaphone around until he 
found the diaphragm that produced the loudest 
sound. This gave him the direction of the 
sound-wave. Then the boat would be steered 
in that direction. He knew that it was aimed 



GETTING THE BEST OF THE U-BOAT 271 

properly when the sound coming to his right ear 
was just as loud as that which came into his left 
ear. 

A still better hydrophone was developed by a 
group of American inventors. The details of 
this cannot yet be disclosed, but we know that 
it was adopted at once by our allies. A very 
sensitive receiver was used which could detect 
a U-boat miles away and determine its direction 
accurately. Under ideal conditions the range 
of the device was from fifteen to twenty-five 
miles, but the average was from three to eight 
miles. If two or more boats fitted with sound- 
detectors were used, they could determine the 
position of the U-boat perfectly. One draw- 
back was that the vessel would have to stop 
so that the noise of its own engines would not 
disturb the listener, but this was largely over- 
come by trailing the detector a hundred feet 
or more from the stern of the ship. The sounds 
were then brought in by an electric cable to the 
listener in the ship. 

These sound-detectors were placed on Allied 
submarines as well as surface vessels and they 
were actually tried out on balloons and dirigi- 
bles, so that they could follow a U-boat after it 



272 INVENTIONS OF THE GREAT V/AR 

had submerged too deeply to be followed by 
sight. 

Many U-boats were chased to their doom by 
the aid of the American hydrophone. Fig. 




OilondtMbncfrical object 
errottc after t*>9 at toe* 



Mtoe*by&C9 



\f-\'Z-/}tts>cfr Unit 10 

Sub bottomed tiers -^/^'^ 

_ Zfc-Attoelrvd 200 
-Stllocbad HGQ 

ffiffistl Arf&SZ-Subtnorina never more & from tts/v 
gs ffevo/ver onota t?aortf 

o "Listening 

» =DepthC/?orys 
— a 3ose Path ofC/rosens 
—*Coi/rse ofJubmorina 



Courtesy of the "Scientific American" 

Fig. 21. Chart of an actual pursuit of a U-boat which, 
ended in the destruction of the submarine 



21 illustrates a very dramatic chase. The full 
line shows the course of the U-boat as plotted 
out by hydrophones and the broken line the 
course of the submarine-chasers. The dots rep- 



GETTING THE BEST OF THE U-BOAT 273 

resent patterns of depth bombs dropped upon 
the U-boat. Try as he would, the Herr Kom- 
mandant could not shake off his pursuers. At 
one time, as the listeners stopped to take obser- 
vations, they heard hammering in the U-boat 
as if repairs were being made. The motors of 
the submarine would start and stop, showing 
clearly that it was disabled. More depth bombs 
were dropped and then there was perfect 
silence, which was soon broken by twenty-five 
revolver-shots. Evidently the crew, unable to 
come to the surface, had given up in despair 
and committed suicide. 

The Adriatic Sea was an ideal place for the 
use of the hydrophone. The water there is so 
deep that submarines dared not rest on the 
bottom, but had to keep moving, and so they 
could easily be followed. Across the sea, at the 
heel of the boot of Italy, a barrage of boats 
was established. U-boats would come down to 
this barrage at night and, when within two or 
three miles of the boats, dive and pass under 
them. But when hydrophones were used that 
game proved very hazardous. Our listeners 
would hear them coming when they were miles 
away. Then they would hear them shift from 



274 INVENTIONS OF THE GREAT WAR 

oil- to electric-drive and plunge under the sur- 
face. Darkness was no protection to the U- 
boats. The sound-detector worked just as well 
at night as in the daytime and a group of three 
boats would drop a pattern of bombs that would 
send the U-boat to the bottom. 

On one occasion after an attack it was evident 
that the submarine had been seriously injured. 
Its motors were operating, but something must 
have gone wrong with its steering-gear, or its 
ballast-chambers may have been flooded, be- 
cause it kept going down -and soon the listeners 
heard a crunching noise as it was crushed by 
the tremendous pressure of the water. 

And so U-boat warfare grew more and more 
terrible for Herr Kommandant. The depths of 
the sea were growing even more dangerous than 
the surface. On every hand he was losing out. 
He had tried to master the sea without master- 
ing the surface of the sea. But he can never 
really master who dares not fight out in the 
open. For a time, the German did prevail, but 
his adversaries were quick to see his deficiencies 
and, by playing upon these, to rob the terror 
of the sea of his powers. And as Herr Kom- 
mandant looks back at the time when he stepped 



GETTING THE BEST OF THE U-BOAT 275 

into the lime-light as the most brutal destroyer 
the world has ever seen, he cannot take much 
satisfaction in reflecting that the sum total of 
his efforts was to spread hatred of Germany 
throughout the world, to summon into the con- 
flict a great nation whose armies turned the tide 
of victory against his soldiers, and finally to 
subject his navy, second only to that of Great 
Britain, to the most humiliating surrender the 
world has ever seen. 



CHAPTEB XIV 

"Devil's Eggs' ' 

IN modern warfare a duel between fixed forts 
and floating forts is almost certain to end 
in a draw. Because the former -are fixed they 
make good targets, while the war-ship, being 
able to move about, can dodge the shell that are 
fired against it. On the other hand, a fort on 
land can stand a great deal of pounding and 
each of its guns must be put out of action in- 
dividually, before it is subdued, while the fort 
that is afloat runs the risk of being sunk with 
a few well-directed shots. 

But fortifications alone will not protect a 
harbor from a determined enemy. They can- 
not prevent hostile ships from creeping by them 
under cover of darkness or a heavy fog. To 
prevent this, the harbor must be mined, and this 
must be done in such a way that friendly ship- 
ping can be piloted through the mine-field, 

276 



"DEVIL'S EGGS" 277 

while hostile craft will be sure to strike the 
mines and be destroyed. 

The mines may be arranged to be fired by 
electricity from shore stations, in which case 
they are anchored at such a depth that ships 
can sail over them without touching them. If a 
hostile vessel tried to dash into the harbor, the 
touch of a button on shore would sink it when 
it passed over one of the mines. But the suc- 
cess of electrically fired mines would depend 
upon the ' ' seeing. ' ' In a heavy fog they would 
prove no protection. 

Another way of using electric mines is to 
have telltale devices which a ship would strike 
and which would indicate to the operator on 
shore that a vessel was riding over the mines 
and would also let him know over which par- 
ticular mines it was at the moment passing. 
No friendly vessel would undertake to enter 
the harbor in a fog or after dark and the oper- 
ator would not hesitate to blow up the invader 
even if he could not see him. 

However, the ordinary method of mining a 
harbor is to lay fields of anchored mines across 
the channels and entrances to the harbor — 
sensitive mines that will blow up at the slight- 



278 INVENTIONS OF THE GREAT WAR 

est touch of a ship's hull — and leave tortuous 
passages through the fields for friendly ship- 
ping. Of course pilots have to guide the ships 
through the passages and lest enemy spies learn 
just where the openings are the mine-fields 
must be shifted now and then. 

The mines are, therefore, made so that they 
can be taken up by friendly mine-sweepers who 
know just how to handle them, and planted else- 
where. These are defensive mines, but there 
are other mines that are not intended to be 
moved. They are planted in front of enemy 
harbors to block enemy shipping and they are 
made so sensitive or of such design that they 
will surely explode if tampered with. 

THE MINE THAT DOES ITS OWN SOUNDING 

A favorite type of mine used during the war 
was one which automatically adjusted itself to 
sink to the desired depth. Submerged mines 
are more dangerous to the enemy because they 
cannot be seen and avoided. They should float 
far enough under the surface to remain hidden 
and yet not so deep that a shallow-draft ship 
can pass over them without hitting them. As 
the sea bottom may be very irregular, it is im- 



"DEVIL'S EGGS" 279 

possible to tell how long the anchor cable should 
be without sounding the depth of the water at 
every point at which a mine is planted. But 
the automatic anchor takes care of this. Very 
ingeniously it does its own sounding and holds 
the mine down to the depth for which it is set. 
The mine cable is wound up on a reel in the 
anchor and the mine is held fast to the anchor 
by a latch. The anchor is of box-shape or 
cylindrical form, with perforations in it. At 
first it sinks comparatively slowly, but as it 
fills with water it goes down faster. Attached 
to the anchor is a plummet or weight, connected 
by a cord to the latch. The length of this cord 
determines the depth at which the mine will 
float. 

The operation of the mine is shown in Fig. 
22. When it is thrown overboard (1) it im- 
mediately turns over so that the buoyant mine 
A floats on the surface (2). While the anchor 
is slowly filling and sinking, the plummet B 
runs out (3). If the mines are to float at a 
depth of, say, ten feet, this cord must be ten 
feet long. As soon as it runs out to its full 
length (4) it springs a latch, C, releasing the 
mine A. Then the mine cable D pays out, as 



280 INVENTIONS OF THE GREAT WAR 

the anchor E sinks, until the plummet B strikes 
bottom (5). As soon as the plummet cord 
slackens a spring-pressed pawl is released and 
locks the mine-cable reel, so that as the anchor 




Courtesy of the "Scientific American" 

Fig. 22. How the mine automatically adjusts itself to vari- 
ous depths of water 



continues to sink it draws the mine down with 
it, until it touches bottom (6), and as the anchor 
was ten feet from the bottom when the plummet 
touched bottom and locked the reel, the mine 



"DEVIL'S EGGS" 281 

must necessarily be dragged down to a depth 
of ten feet below the surface. 

The mine itself, «or the "devil's egg" as it 
is called, is usually a big buoyant sphere of 
metal filled with TNT or some other power- 
ful explosive; and projecting from it are a 
number of very fragile prongs which if broken 
or even cracked will set off the mine. There 
is a safety-lever or pin that makes the mine 
harmless when it is being handled, and this 
must be withdrawn just before the mine is to 
be launched. In some mines the prongs are 
little plungers that are withdrawn into the 
mine-shell and held by a cement which softens 
after the mine is submerged and lets the 
plungers spring out. When the plungers are 
broken, water enters and, coming in contact 
with certain chemicals, produces enough heat to 
set off a cartridge which fires the mine. 

PICKING INFERNAL MACHINES OUT OF THE SEA 

The enemy mine-fields were often located 
by seaplanes and then mine-sweepers had to 
undertake the extremely hazardous task of rais- 
ing the mines or destroying them. If they 
were of the offensive type, it was much better 



282 INVENTIONS OF THE GREAT WAR 

to destroy them. But occasionally, when con- 
ditions permitted, mine-sweepers undertook to 
raise the mines and reclaim them for future use 
against the enemy. The work of seizing a mine 
and making it fast to the hoisting-cable of the 
mine-sweeper was usually done from a small 
rowboat. Eaising the first mine was always 
the most perilous undertaking, because no one 
knew just what type of mine it was and how to 
handle it with safety, or whether there was any 
way in which it could be made harmless. There 
were some mines, for instance, that contained 
within them a small vial partly filled with 
sulphuric acid. The mine carried no prongs, 
but if it were tilted more than twenty degrees 
the acid would spill out and blow up the mine. 
Such a mine would be exceedingly difficult if 
not impossible to handle from a boat that was 
rocked about by the waves. 

After the first mine of the field was raised 
and its safety-mechanism studied, the task of 
raising the rest was not so dangerous. A 
water telescope was used to locate the mine and 
to aid in hooking the hoisting-cable into the 
shackle on the mine. The hook was screwed 
to the end of a pole and after the mine was 



"DEVIL'S EGGS" 283 

hooked, the pole was unscrewed and the cable 
hauled in, bringing up the "devil's egg" 
bristling with death. Care had to be taken to 
keep the bobbing boat from touching the deli- 
cate prongs until the safety-device could be 
•set. 

However, this painstaking and careful 
method of raising mines was not often em- 
ployed. Shallow-draft mine-sweepers would 
run over the mine-field, dragging a cable be- 
tween them. The cable would be kept down by 
means of hydrovanes or "water kites' ' deep 
enough to foul the anchor cables of the mines. 
The "water kites" were V-shaped structures 
that were connected to the cable in such a way 
that they would nose down as they were 
dragged through the water and carry the cable 
under. The action is just the reverse of a kite, 
which is set to nose up into the wind and carry 
the kite up when it is dragged through the air. 
By means of the cable the anchor chain of the 
mine was caught and then the mine with its 
anchor was dragged up. If the mine broke 
loose from its anchor it could be exploded with 
a rifle-shot if it did not automatically explode 
on fouling the cable. 



284 INVENTIONS OF THE GREAT WAR 

FLOATING MINES 

When England entered the war she mined her 
harbors because, although she had the mastery 
of the sea, she had to guard against raids of 
enemy ships carried out in foggy and dark 
weather. But the mines were no protection 
against submarines. They would creep along 
the bottom under the mines. Then cable nets 
were stretched across the harbor channels to 
bar the submarines, but the U-boats were 
fitted with cutters which would tear through 
the nets, and it became necessary to use mines 
set at lower depths so that the submarines could 
not pass under them; and nets were furnished 
with bombs which would explode when fouled 
by submarines. In fact, mines were set adrift 
with nets stretched between them, to trap sub- 
marines. Floating mines were also used by the 
Germans for the destruction of surface vessels 
and these were usually set adrift in pairs, with 
a long cable connecting them, so that if a vessel 
ran into the cable the mines would be dragged 
in against its hull and blow it up. 

The laws of war require that floating mines be 



"DEVIL'S EGGS" 285 

of such a design that they will become inopera- 
tive in a few hours ; otherwise they might drift 
about for weeks or months or years and be a 
constant menace to shipping. Sometimes 
anchored mines break away from their moor- 
ings and are carried around by ocean currents 
or are blown about by the winds. A year 
after the Eusso-Japanese War a ship was 
blown up by striking a mine that had been torn 
from its anchorage and had drifted far from 
the field in which it was planted. No doubt 
there are hundreds of mines afloat in the 
Atlantic Ocean which for many years to come 
will hold out the threat of sudden destruction 
to ocean vessels ; for the Germans knew no laws 
of war and had no scruples against setting 
adrift mines that would remain alive until they 
were eaten up with rust. 

The chart on the next page shows the course 
of ocean currents in the North Atlantic as 
plotted out by the Prince of Monaco, from which 
it may be seen that German mines will prob- 
ably make a complete circuit of the North 
Atlantic, drifting down the western coast of 
Europe, across the Atlantic, around the Azores, 



286 INVENTIONS OF THE GREAT WAR 

and into the Gulf Stream, which will carry them 
back to the North Sea, only to start all over. 
(See Fig. 23.) Some of them will run up into 
the Arctic Ocean, where they will be blown up 
by striking icebergs and many will be trapped 
in the mass of floating 
seaweed in the Sargasso 
Sea. But many years 
will pass before all dan- 
ger of mines will be re- 




Courtesy of the "Scientific American." 

Fig. 23. Ocean currents of the North Atlantic showing the 
probable path of drifting mines 



moved. In the meantime, the war has left a 
tremendous amount of work to be done in rais- 
ing anchored mines and destroying them. 



"DEVIL'S EGGS" 287 



EGG-IAYING SUBMAEIKES 



Early in the war the British were astonished 
to find enemy mine-fields in their own waters, 
far from any German ports. They could not 
have been planted by surface mine-layers, un- 
less these had managed to creep up disguised 
as peaceful trawlers. This seemed hardly 
likely, because these fields appeared in places 
that were well guarded. Then it was dis- 
covered that German U-boats were doing this 
work. Special mine-laying U-boats had been 
built and one of them was captured with 1 its 
cargo of "devil's eggs." 

A sectional view of the mine-laying U-boat 
is shown opposite page 272. In the after part 
of the boat were mine-chutes in each of which 
three mines were stored. A mine-laying sub- 
marine would carry about a score of mines. 
These could be released one at a time. The 
mine with its anchor would drop to the bottom. 
As soon as it struck, anchor-arms would be 
tripped and spread out to catch in the sand or 
mud, while the mine cable would be released 
and the mine would rise as far as the cable 
would allow it. The U-boat commander would 



288 INVENTIONS OF THE GREAT WAR 

have to know the depth of water in which 
the mines were to be laid and adjust the cables 
to this depth in advance. This could not be 
done while the U-boat was submerged. With 
the mines all set for the depth at a certain spot, 
the U-boat commander had to find that very 
spot to lay his "eggs," otherwise they would 
either lie too deep to do any harm to shipping, 
or else they would reach up to the surface, 
where they might be discovered by the Allied 
patrols. As he had to do his navigating blindly, 
by dead-reckoning, it was very difficult for him 
to locate his mine-fields properly. 

But the Germans did not have a monopoly 
on submarine mine-laying. The British also 
laid mines by submarine within German har- 
bors and channels, right under the guns of 
Heligoland, and many a U-boat was destroyed 
by such mines within its home waters. 

PARAVANES 

On the other hand, the Allies had a way of 
sailing right through fields of enemy mines 
with little danger. Our ships were equipped 
with " paravanes' ' which are something like 
the " water kites' ' used by mine-sweepers, and 




» 







Courtesy of "Scientific American " 

Hooking Up Enemy Anchored Mines 



" DEVIL'S EGGS" 289 

they are still used in the waters of the war zone. 
Paravanes are steel floats with torpedo-shaped 
bodies and a horizontal plane near the for- 
ward end. At the tail of the paravane, there 
are horizontal and vertical rudders which can be 
set to make the device run out from the side of 
the vessel that is towing it, and at the desired 
depth below the surface. Two paravanes are 
used, one at each side of the ship, and the tow- 
ing-cables lead from the bow of the vessel. 
Thus there are two taut cables that run out 
from the ship in the form of a V and at such a 
depth that they will foul the mooring-cable of 
any mine that might be encountered. The mine 
cable slides along the paravane cable and in 
this way is carried clear of the ship's hull. 
When it reaches the paravane it is caught in a 
sharp-toothed jaw which cuts the mine cable and 
lets the mine bob up to the surface. The mine 
is then exploded by rifle or machine-gun fire. 
In some forms of paravane there is a hinged 
jaw which is operated from the ship to shear the 
cable. The jaw is repeatedly opened and 
closed by a line that runs to a winch on the ship. 
This winch winds up the line until it is taut 
and then the line is permitted to slip, letting 



290 INVENTIONS OF THE GREAT WAR 

the jaw open, only to close again as the winch 
keeps on turning and winding up the line. 

Guarded by steel sharks on each side, their 
jaws constantly working, a ship can plow right 
through a field of anchored mines with little 
danger. To be sure, the bow might chance to 
hit a mine, when, of course, there would be an 
explosion ; but the ship could stand damage here 
better than anywhere else and unless the bow 
actually hit the mine, one or other of the para- 
vanes would take care of it and keep it from 
being dragged in against the hull of the vessel. 

PENNING IN THE U-BOATS 

According to German testimony, mines were 
responsible for the failure of the U-boat. How- 
ever, it was not merely the scattered mine- 
fields sown in German waters that brought the 
U-boat to terms, but an enormous mine-field 
stretching across the North Sea from the Orkney 
Islands to the coast of Norway. Early in the 
war, U-boats had been prevented from entering 
the English Channel by nets and mines stretched 
across the Straits of Dover. As the submarine 
menace grew, it was urged that a similar net 
be stretched across the North Sea to pen the 



"DEVIL'S EGGS" 291 

U-boats in. But it seemed like a stupendous 
task. The distance across at the narrowest 
point is nearly two hundred and fifty miles. 
It would not have been necessary to have the 
net come to the surface. It could just as well 
have been anchored so that its upper edge 
would be covered with thirty feet of water. 
Surface vessels could then have sailed over it 
without trouble and submarines could not have 
passed over it without showing themselves to 
patrolling destroyers. It would not have been 
necessary to carry the net to the bottom of the 
sea. A belt of netting a hundred and fifty feet 
wide would have made an effective bar to the 
passage of U-boats. As U-boats might cut their 
way through the net, it was proposed to mount 
bombs or mines on them which would explode on 
contact and destroy any submarine that tried to 
pass. However, laying a net two hundred feet 
long even when it is laid in sections, is no small 
job, but when the net is loaded with contact 
mines, the difficulty of the work may be well 
imagined. 

And yet had it been thought that the net would 
be a success it would have been laid anyhow, 
but it was argued that seaweed would clog the 



292 INVENTIONS OF THE GEEAT WAR 

meshes of the net and ocean currents would tear 
gaps in it. Even if it had not been torn away, 
the tidal currents would have swept it down and 
borne it under so far that U-boats could have 
passed over it in safety without coming to the 
surface. 

A WALL OF MIXES 

When America entered the war, we were very 
insistent that something must be clone to block 
the North Sea, and we proposed that a barrage 
of anchored mines be stretched across the sea 
and that these mines be set at different levels 
so as to make a "wall" that submarines could 
not dive under. This would do away with all 
the drawbacks of a net. Ocean currents and 
masses of seaweed could not affect individual 
mines as they would a net. Furthermore, an 
American inventor had devised a new type of 
mine which was peculiarly adapted to the pro- 
posed mine barrage. It had a firing-mechan- 
ism that was very sensitive and the mine 
had twice the reach of any other. 

At length the British mine-laying forces were 
prevailed upon to join with us in laying this 
enormous mine, It was one of the biggest and 



"DEVIL'S EGGS" 293 

most successful undertakings of the war. It 
was to be two hundred and thirty miles long 
and twelve miles wide on the average, reaching 
from the rocky shores of the Orkney Islands 
to Norway. There was plenty of deep water 
close to the coast of Norway and it was against 
international law to lay mines within three miles 
of the shores of a neutral nation, so that the U- 
boats might have had a clear passage around the 
end of the barrage. But as it was also against 
the law for the U-boats to sail through neutral 
waters, Norway laid a mine-field off its coast 
to enforce neutrality, and this was to join with 
that which the British and we were to lay. 
Most of the mine-laying was to be done by the 
United States and we were to furnish the mines. 
The order to proceed witlrthe work was given 
in October, 1917, and it was a big order. A 
hundred thousand mines were to be made and to 
preserve secrecy, as well as to hurry the work 
as much as possible, it was divided among five 
hundred contractors and subcontractors. The 
parts were put together in one plant and then 
sent to another, where each mine was filled with 
three hundred pounds of molten TNT. To 
carry them across the ocean small steamers 



294 INVENTIONS OF THE GREAT WAR 

were used, so that if one should be blown up 
by a submarine the loss of mines would not be 
very great. There were twenty-four of these 
steamers, each carrying from twelve hundred to 
eighteen hundred mines and only one of them 
was destroyed by a submarine. The steamers 
delivered their loads on the west coast of Scot- 
land and the mines were taken across to the 
east coast by rail and motor canal-boats. Here 
the mines were finally assembled, ready for 
planting. Seventy thousand mines were 
planted, four fifths of them by American mine- 
layers and the rest by the British. 

MINE EAILKOADS ON SHIPS 

To handle the mines the ships were specially 
fitted with miniature railroads for transporting 
the mines to the launching-point, so that they 
could be dropped at regular intervals without 
interruption. Each anchor mine was provided 
with flanged wheels that ran on rails. The 
mines were carried on three decks and each 
deck was covered with a network of rails, 
switches, and turn-tables, while elevators were 
provided to carry the mines from one deck to 
another. The mines, like miniature railroad 



"DEVIL'S EGGS" 295 

cars, were coupled up in trains of thirty or forty 
and as each mine weighed fourteen hundred 
pounds, steam winches had to be used to haul 
them. At the launching-point the tracks ran out 
over the stern of the boat and here a trap was 
provided which would hold only one mine at a 
time. By the pulling of a lever the jaws of the 
trap would open and the mine would slide off the 
rails and plunge into the sea. 

The mines were dropped every three hundred 
feet in lines five hundred feet apart, as it was 
unsafe for the mine-layers to steam any closer 
to one another than that. The mines were of 
the type shown in Fig. 22 and automatically 
adjusted themselves to various depths. The 
depth of the water ran down to twelve hundred 
feet near the Norwegian coast. Never before 
had mines been planted at anywhere near that 
depth. 

It was dangerous work, because the enemy 
knew where the mines were being planted, as 
neutral shipping had to be warned months in ad- 
vance. The mine-layers were in constant 
danger of submarine attack, although they were 
convoyed by destroyers to take care of the 
U-boats. There was- even danger of a surface 



296 INVENTIONS OF THE GREAT WAR 

attack and so battle-cruisers were assigned the 
job of guarding the mine-layers. The mine- 
layers steamed in line abreast, and had one of 
them been blown up, the shock would probably 
have been enough to blow up the others as well. 
Enemy mines were sown in the path of the 
mine-layers, so the latter had to be preceded by 
mine- sweepers. Navigation buoys had to be 
planted at the ends of the lines of mines and the 
enemy had a habit of planting mines near the 
buoys or of moving the buoys whenever he had 
a chance. But despite all risks the work was 
carried through. 

The barrier was not an impassable one. With 
the mines three hundred feet apart, a submarine 
might get through, even though the field was 
twenty-five miles broad, but the hazards were 
serious. Before the first lines of mines had been 
extended half-way across, its value was demon- 
strated by the destruction of several U-boats, 
and as the safety-lane was narrowed down the 
losses increased. It is said that altogether 
twenty-three German submarines met their 
doom in the great mine barrage. U-boat com- 
manders balked at running through it, and 
U-boat warfare virtuallv came to a standstill. 



11 DEVIL'S EGGS" 297 

According to Captain Bartenbach, commander 
of submarine bases in Flanders, three U-boats 
were sunk by anchored mines for every one that 
was destroyed by a depth bomb. 



CHAPTEE XV 

Surface Boats 

THE war on the submarine was fought 
mainly from the surface of the sea and 
from the air above the sea, and naturally it 
resulted in many interesting naval develop- 
ments. 

As described in Chapter XIII, the first offen- 
sive measure against the U-boat was the build- 
ing of swarms of speedy motor-boats which 
drove the invaders away from harbors and into 
the open sea. To follow the U-boats out into 
rough water larger submarine-chasers were 
built, but even they could not cope with the 
enemy far from the harbors. 

MOTOE TORPEDO-BOATS 

The Italians made excellent use of speedy 
motor-boats in the protected waters of the Adri- 
atic Sea. One type of motor-boat was equipped 

298 



SURFACE BOATS 299 

with two torpedo-tubes in the bow 1 . Small 14- 
inch torpedoes were used, but as each torpedo 
carried two hundred pounds of high explosive, 
the motor-boat was a formidable vessel if it 
crept in close enough to discharge one of these 
missiles at its foe. 

On one occasion, a patrol of these little boats 
sighted a couple of Austrian dreadnoughts 
headed down the coast, surrounded by a screen 
of ten destroyers. Favored by the mist, two of 
the motor-boats crept through the screen of de- 
stroyers, and torpedoed the battle-ships. Then 
they made good their escape. A destroyer that 
pursued one of the boats decided that the game 
was not worth while when it was suddenly 
shaken up by the explosion of a depth bomb 
dropped from the motor-boat. 

THE SEA TANK 

The Italians showed a great deal of naval in- 
itiative. They were forever trying to trap the 
Austrian fleet or to invade its harbors. Like 
all other naval powers, the Austrians protected 
their harbors with nets and mines. It was im- 
possible for submarines to make an entrance and 
the ports were too well fortified to permit an 



300 INVENTIONS OF THE GREAT WAR 

open attack on the surface. Nevertheless, the 
Italians did break through the harbor defenses 
on one or two occasions and sank Austrian war- 
vessels. Again it was with a small boat that 
they did the trick. 

The nets which the Austrians stretched across 
their harbor entrance were supported on wooden 
booms or logs which served as floats. These 
booms offered an effective bar to small boats 
which might attempt to enter the harbor under 
cover of darkness. But the Italians found a 
way to overcome this obstruction. They built 
a flat-bottomed motor-boat which drew very 
little water. Running under the boat were two 
endless chains, like the treads of a tank. In 
fact, the boat came to be known asa u sea tank. ' ' 
The chains were motor-driven and had spiked 
sprockets, so that when a boom was encountered 
they would bite into the wood and pull the boat 
up over the log, or maybe they would drag the 
log down under the boat. At any rate, with this 
arrangement it was not very difficult to pass the 
boom and enter the harbor. At the rear the 
chains were carried back far enough to prevent 
the propeller from striking when the boat had 
passed over the log. 




bo 

.5 

g 



< 



SURFACE BOATS 301 

THE AWKWARD "EAGLES" 

A curious boat that we undertook to furnish 
during the war was a cross between a destroyer 
and a submarine-chaser. After the submarine 
had been driven out to sea its greatest foe was 
undoubtedly the destroyer, and frantic efforts 
were made to turn out as many destroyers as 
possible. But it takes time to build destroyers 
and so a new type of boat was designed, to be 
turned out quickly in large numbers. A hun- 
dred and ten " Eagles " (as these boats are 
called) were ordered, but the armistice was 
signed before any of them were put into service ; 
and it is just as well that such was the case, for 
in their construction everything was sacrificed 
to speed of production. As a consequence they 
are very ugly boats, with none of the fine lines 
of a destroyer, and they roll badly, even when 
the sea is comparatively peaceful. They are 
five-hundred-ton boats designed to make eight- 
een knots, which would not have been fast 
enough to cope with U-boats, because the latter 
could make as high a speed as that themselves, 
when traveling on the surface, and the two 
4-inch guns of the Eagles would have been far 



302 INVENTIONS OF THE GREAT WAR 

outranged by the 5.9-inch guns of the larger 
U-boats. 

SEAPLANE TOWING-BARGES 

When the war on the U-boat was carried up 
into the sky, many new naval problems cropped 
up, particularly when German submarines 
chose to work far out at sea. Big seaplanes 
were used, but they consumed a great deal of 
fuel in flying out and back, cutting down by just 
so much their flying-radius at the scene of activi- 
ties. A special towing-barge was used. These 
barges had trimming-tanks aft, which could be 
flooded so that the stern of the barge would sub- 
merge. A cradle was mounted to run on a pair 
of rails on the barge. The body of the seaplane 
was lashed to this cradle and then drawn up on 
the barge by means of a windlass. This done, 
the water was blown out of the trimming- tanks 
by means of compressed air and the barge was 
brought up to an even keel. The barge with 
its load was now ready to be towed by a de- 
stroyer or other fast boat to the scene of opera- 
tions. There water was again let into the 
trimming-tanks and the seaplane was let back 



SURFACE BOATS 30S 

into the water. From the water the seaplane 
arose into the air in the usual way. 

Unfortunately, when the sea is at all rough 
it is exceedingly difficult for a seaplane to take 
wing, particularly a large seaplane. A better 
starting-platform than the sea had to be fur- 
nished. At first some seaplanes were furnished 
with wheels, so that they could be launched from 
platforms on large ships; and then, to increase 
the flying-radius, seaplanes were discarded in 
favor of airplanes. Once these machines were 
launched, there was no way for them to get 
back to the ship. They had to get back to land 
before their fuel was exhausted. 

On the large war-vessels -a starting-platform 
was built on a pair of long guns. Then the 
war-ship would head into the wind and the com- 
bined travel of the ship and of the airplane 
along the platform gave speed -enough to raise 
the plane off the platform before it had run the 
full length of the guns. But as long as aviators 
had no haven until they got back to land, there 
were many casualties. Eager to continue their 
patrol as long as possible, they would some- 
times linger too long before heading for home 



304 INVENTIONS OF THE GREAT WAR 

and then they would not have enough fuel left 
to reach land. Many an aviator was lost in this 
way, and finally mother-ships for airplanes had 
to be built. 

THE 

The British Navy had constructed a number of 
very fast cruisers to deal with any raiders the 
Germans might send out. These cruisers were 
light vessels capable of such high speeds that 
they could even overtake a destroyer. They 
were 840 feet long and their turbines developed 
90,000 horse-power. The construction of these 
vessels was for a long time kept a profound 
secret and it was not until the German fleet 
surrendered that photographs of them were al- 
lowed to be published. Because of this secrecy 
the boats were popularly known as " hush- 
ships. " They were not armored; it was not 
necessary to load them down with armor plate, 
because their protection lay in speed and they 
were designed to fight at very long range. In 
fact, they were to carry guns that would out- 
range those of the most powerful dreadnoughts. 
Our largest naval guns are of 16-inch caliber, 
but the "hush ships' ' were each to carry two 



SURFACE BOATS 305 

18-inch guns. The guns were monsters weigh- 
ing 150 tons each and they fired a shell 18 inches 
in diameter and 7 feet long to a distance of 30 
miles when elevated to an angle of 45 degrees. 
The weight of the shell was 3600 pounds and it 
carried 500 pounds of high explosive or more 
than is carried in the largest torpedoes. 

At the 32-mile range the shell would pass 
through 12 inches of face-hardened armor and 
at half that range it would pass through armor 
18 inches thick, and there is no armor afloat, any 
heavier than this. 

MOTHER-BOATS FOR AIRPLANES 

Armed with such powerful guns as these, the 
' ' hush ships" would have been very formidable 
indeed; but when the guns were mounted on one 
of the cruisers, the Furious, they were found 
too powerful for the vessel. It was evident that 
the monsters would very •seriously rack their 
own ship. So the guns were taken off the 
cruiser and it was turned into a mother-ship 
for airplanes. A broad, unobstructed deck was 
built on the ship which provided a runway from 
which airplanes could be launched, and this run- 
way was actually broad enough to permit air- 



MM 



306 INVENTIONS OF THE GREAT WAR 

planes to land upon it. Under the runway were 
the hangars in which the airplanes were housed. 
Other "hush ships" were also converted into 
airplane mother-boats and there were special 
boats built for this very purpose, although they 
were not -able to make the speed of the "hush 
ships. ' ' One of these special boats had funnels 
that turned horizontally to carry off the furnace 
smoke over the stern and leave a perfectly clear 
flying-deck, 330 feet long. 

TORPEDO-PROOF MONSTERS 

As for the 18-inch guns, they were put to an- 
other use. Early in the war the British had 
need for powerful shallow-draft vessels which 
could operate off the Flanders coast and attack 
the coast fortifications that were being built by 
the Germans. The ships that were built to 
meet this demand were known as monitors, be- 
cause like the famous "monitor' ' of our Civil 
War they carried a single turret. These moni- 
tors were very broad for their length and were 
very slow. At best they could make only seven 
knots and in heavy weather they could not make 
more than two or three knots. 

To be made proof against torpedoes these 



SURFACE BOATS 307 

boats were formed with "blisters" or hollow 
rounded swells in the hull at each side which 
extended out to a distance of twelve to fifteen 
feet. The blisters were subdivided into com- 
partments, so that if a torpedo struck the ship 
it would explode against a blister at a consider- 
able distance from the real hull of the ship and 
the force of the explosion would be expended 
in the compartments. The blisters were the 
salvation of the monitors. Often were the boats 
struck by torpedoes without being sunk. 

Unfortunately, this form of protection could 
not be applied to ordinary vessels, because it 
would have interfered seriously with navigation. 
The blisters made the monitors very difficult 
to steer and hampered the progress of a ship, 
particularly in a seaway. 

With ships such as these the British bom- 
barded Zeebrugge from a distance of twenty to 
twenty-five miles. Of course, the range had to 
be plotted out mathematically, as the target was 
far beyond the horizon of the ship, and the 
firing had to be directed by spotters in air- 
planes. 

At first guns from antiquated battle-ships 
were used in the monitors; then larger guns 



308 INVENTIONS OF THE GREAT WAR 

were used, until finally two of the monitors in- 
herited the 18-inch guns of the Furious. A 
single gun was mounted on the after deck of each 
vessel and the gun was arranged to fire only 
on the starboard side. No heavily armored 
turret was provided, but merely a light housing 
to shelter the gun. 

AN ELECTKICALLY STEEEED MOTOB-BOAT 

The British war-vessels that operated in the 
shallow waters off the coast of Flanders were a 
constant source of annoyance to the Germans. 
Because of the shallow water it was seldom pos- 
sible for a submarine to creep up on them. A 
U-boat required at least thirty-five feet of water 
for complete submergence and it did not dare 
to attack in the open. This led the Germans to 
launch a motor-boat loaded with high explosive, 
which was steered from shore. The motor- 
boat carried a reel of wire which connected it 
with an operator on shore. There was no pilot 
in the boat, but the helm was controlled elec- 
trically by the man at the shore station. As it 
was diff cult for the helmsman to see just what 
his boat was doing, or just how to steer it when 
it was several miles off, an airplane flew high 



SURFACE BOATS 309 

above it and directed the helmsman, by radio- 
telegraphy, how to steer his boat. Of course, 
radiotelegraphy might have been used to 
operate the steering-mechanism of the boat, 
but there was the danger that the radio oper- 
ators of the British might send out disturbing 
waves that would upset the control of the motor- 
boat, and so direct wire transmission was used 
instead. Fortunately, when the Germans tried 
this form of attack, an alert British lookout dis- 
covered the tiny motor-boat. The alarm was 
given and a lucky shot blew up the boat with 
its charge before it came near the British vessel. 



CHAPTEE XVI 

Reclaiming the Victims of the Submarine 

NEARLY fifteen million tons of shipping lie 
at the bottom of the sea, sunk by German 
U-boats, and the value of these ships with their 
cargo is estimated at over seven billion dollars. 
In one year, 1917, the loss was nearly a million 
dollars a day. 

Of course these wrecks would not be worth 
anything like that now, if they were raised and 
floated. Much of the cargo would be so dam- 
aged by its long immersion in salt water that it 
would be absolutely valueless, but there are 
many kinds of merchandise that are not injured 
in -the least by water. Every ship carries a cer- 
tain -amount of gold and silver; -and then the 
ship 's hull itself is well worth salving, provided 
it was not too badly damaged by the torpedo 
that sank it. Altogether, there is plenty of rich 
treasure in the sea awaiting the salvor who is 
bold enough to go after it. 

310 



VICTIMS OF THE SUBMARINE 311 

To be sure, not all of the U-boat's victims 
were sunk in deep water. Many torpedoed ves- 
sels were beached or succeeded in reaching shal- 
low water before they foundered. Some were 
sunk in harbors while they lay at anchor, before 
the precaution was taken of protecting the har- 
bors with nets. The Allies did not wait for the 
war to end before trying to refloat these- vessels. 
In fact, during the war several hundred ships 
were raised and put back into service. A 
special form of patch was invented to close 
holes torn by torpedoes. Electric pumps were 
built which would work under water and these 
were lowered into the holds of ships to pump 
them out. The salvors were provided with 
special gas-masks to protect them from poison- 
ous fumes of decayed matter in the wrecks. 

Our own navy has played an important part 
in salvage. Shortly after we entered the war, 
all the wrecking-equipment in this country was 
commandeered by the government and we sent 
over to the other side experienced American sal- 
yors, provided with complete equipment of appa- 
ratus and machinery. 

The majority of wrecks, however, are found 
in the open sea, where it would have been foolish 



312 INVENTIONS OF THE GREAT WAR 

to attempt any salvage-operations because of the 
menace of submarine attack. On at least one 
occasion a salvage vessel, while attempting to 
raise the victims of a submarine, fell, itself, a 
prey to a Hun torpedo. Now that this menace 
has been removed, such vessels as lie in com- 
paratively shallow water, and in positions not 
subject to sudden tempests, can be raised by the 
ordinary methods; or if it is impracticable to 
raise them, much of their cargo can be reclaimed. 
However, most of the torpedoed ships lie at 
such depths that their salvage would ordinarily 
be despaired of. 

IN THE DEPTHS OF THE SEA 

It will be interesting to look into conditions 
that exist in deep water. Somehow the notion 
has gone forth that a ship will not surely sink 
to the very bottom of the deep sea, but on reach- 
ing a certain level will find the water so dense 
that even solid iron will float, as if in a sea of 
mercury, and that here the ship will be main- 
tained in suspension, to be carried hither and 
yon by every chance current. Indeed, it makes 
a rather fantastic picture to think of these los't 
ships drifting in endless procession, far down 



VICTIMS OF THE SUBMARINE 313 

beneath the cold green waves, and destined to 
roam forever like doomed spirits in a circle of 
Dante's Inferno. 

But the laws of physics shatter any such illu- 
sion and bid us paint a very different picture. 
Liquids are almost incompressible. The differ- 
ence in density between the water at the surface 
of the sea and that at a depth of a mile is almost 
insignificant. As a matter of fact, at that depth 
the water would support only about half a 
pound more per cubic foot than at the surface. 
The pressure, however, would be enormous. 
Take the Titanic, for instance, which lies on the 
bed of the ocean in water two miles deep. It 
must endure a pressure of about two long tons 
on every square inch of its surface. Long be- 
fore the vessel reached the bottom her hull 
must have been crushed in. Every stick of 
wood, every compressible part of her structure 
and of her cargo, must have been staved in or 
flattened. As a ship sinks it is not the water but 
the ship that grows progressively denser. The 
Titanic must have actually gained in weight as 
she went down, and so she must have gathered 
speed as she sank. 

We may be certain, therefore, that every vic- 



wm 



314 INVENTIONS OF THE GREAT WAR 

tim of Germany's ruthless U-boats that sank 
in deep water lies prone upon the floor of the 
sea. It matters not how or where it was sunk, 
whether it was staggered by the unexpected blow 
of the torpedo and then plunged headlong into 
the depths of the sea, or whether it lingered, 
mortally wounded, on the surface, quietly 
settling down until the waves closed over it. 
Theoretically, of course, a perfect balance might 
be reached which would keep a submerged ves- 
sel in suspension, but practically such a condi- 
tion is next to impossible. Once a ship has 
started down, she will keep on until she reaches 
the very bottom, whether it be ten fathoms or 
ten hundred. 

A SUBMARINE GBAVEYAKD 

Instead of the line of wandering specters, 
then, we must conjure up a different picture, 
equally weird — an under-world shrouded in 
darkness; for little light penetrates the deep 
sea. Here in the cold blackness, on the bed of 
the ocean, the wrecks of vessels that once sailed 
proudly overhead lie still and deathly silent — 
some keeled over on their sides, some turned 



VICTIMS OF THE SUBMARINE 315 

turtle, and most of them probably on even keel. 
Here and there may be one with its nose buried 
deep in the mud; and in the -shallower waters 
we may come across one pinned down by the 
stern, but with its head buoyed by a pocket of 
air, straining upward and swaying slightly with 
every gentle movement of the sea, as if still 
alive. 

This submarine graveyard offers wonderful 
opportunities for the engineer, because the rais- 
ing of wrecked vessels is really a branch of en- 
gineering. It is a very special branch, to be 
sure, and one that has not begun to receive 1 the 
highly concentrated study that have such other 
branches as tunneling, bridge-construction, etc. 
Nevertheless it is engineering, and it has been 
said of the engineer that his abilities are limited 
only by the funds at his disposal. Now he has 
a chance to show what he can do, for there are 
hundreds of vessels to be salved where before 
there was but one. The vast number of wrecks 
in deep water will make it pay to do the work 
on a larger and grander scale than has been 
possible heretofore. Special apparatus that 
could not be built economically for a single 



316 INVENTIONS OF THE GREAT WAR 

wreck may be constructed with profit if a num- 
ber of vessels demanding similar treatment are 
to be salved. 

The principal fields of German activities were 
the Mediterranean Sea and the waters surround- 
ing the British Isles. Although the submarine 
zone covered some very deep water, where the 
sounding-lead runs down two miles without 
touching bottom, obviously more havoc could 
be wrought near ports where vessels were 
obliged to follow a prescribed course, and so 
most of the U-boat victims were stricken when 
almost in sight of land. In fact, as was pointed 
out in a previous chapter, it was not until ef- 
ficient patrol measures made it uncomfortable 
for the submarines that they pushed out into the 
open ocean to pursue their nefarious work. 
The Lusitania went down only eight miles from 
Old Head of Kinsale, in fifty fathoms of water. 

If we draw a line from Fastnet Eock to the 
Scilly Islands and from there to the western- 
most extremity of France, we enclose an area 
in which the German submarines were particu- 
larly active. The soundings here run up to 
about sixty fathoms in some places, but the pre- 
vailing depth is less than fifty fathoms. In 



VICTIMS OF THE SUBMARINE 317 

the North Sea, too, except for a comparatively 
narrow lane along the Norwegian coast — which, 
by the way, marked the safety lane of the Ger- 
man blockade zone — the chart shows fifty 
fathoms or under. If our salvors could reach 
down as far as that, most of the submarine 
victims could be reclaimed. But fifty fathoms 
means 300 feet, which is a formidable depth 
for salvage work. Only one vessel has ever 
been brought up from such a depth and that 
was a small craft, one of our submarines, the 
F-4, which sank off the coast of Hawaii four 
years ago. 

DIFFEEENT WAYS OF SALVING A WEECK 

There are. four well-known methods of rais- 
ing a vessel that is completely submerged. Of 
course, if the ship is not completely submerged, 
the holes in her hull may be patched up, and 
then when her hull is pumped out, the sea itself 
will raise the ship, unless it be deeply embedded 
in sand or mud. If the vessel is completely 
submerged, the same process may be resorted 
to, but first the sides of the hull must be ex- 
tended to the surface to keep the water from 
flowing in as fast as it is pumped out. It is 



318 INVENTIONS OF THE GREAT WAR 

not usual to build up the entire length of the 
ship. If the deck is in good condition, it may 
suffice to construct coffer-dams or walls around 
several of the hatches. But building up the 
sides of a ship, or constructing corf er-dams on 
the ship's deck is a difficult task, at best, because 
it must be done under water by divers. 

A record for this type of salvage work was 
established by the Japanese when they raised 
the battle-ship Mikasa that lay in some eighty 
feet of water. Her decks were submerged to a 
depth of forty feet. It is doubtful that this 
salvage work could be duplicated by any other 
people of the world. The wonderful patriot- 
ism and loyalty of the Japanese race were called 
forth. It is no small task to build a large coffer- 
dam strong enough to withstand the weight of 
forty feet of water, or a pressure of a ton and a 
quarter per square foot, even when the work is 
done on the surface. Perfect discipline and or- 
ganized effort of the highest sort were required. 
Labor is cheap in Japan and there was no 
dearth of men for the work. Over one hundred 
divers were employed. In addition to the cof- 
fer-dam construction much repair work was nec- 
cessary. Marvelous acts of devotion and hero- 



VICTIMS OF THE SUBMARINE 319 

ism were performed. It is rumored that in 
some places it was necessary for divers to close 
themselves in, cut their air supply-pipes and 
seal themselves off from the slightest chance 
of escape; and that there were men who actu- 
ally volunteered to sacrifice their lives in this 
way for their beloved country and its young 
navy. Where, indeed, outside of the Land of 
the Rising Sun could we find such patriotic de- 
votion ! 

A second salvage method consists in building 
a coffer-dam not on the ship but around it, 
and then pumping this out so as to expose 'the 
ship as in a dry-dock. Such was the plan fol- 
lowed out in recovering the Maine. Obviously, 
it is a very expensive method and is used only 
in exceptional cases, such as this, in which it 
was necessary to make a post-mortem examina- 
tion to determine what caused the destruction 
of the vessel. Neither of these methods of sal- 
vage will serve for raising a ship sunk in deep 
water. 

KAISING A SHIP ON AIK 

A salvage system that has come into promin- 
ence within recent years consists in pumping 



320 INVENTIONS OF THE GREAT WAR 

air into the vessel to drive the water out, thus 
making the boat light enough to float. This 
scheme can be used only when the deck and 
bulkheads of the boat are strongly built and 
able to stand the strain of lifting the wreck, 
and when the hole that sank the vessel is in or 
near the bottom, so as to allow enough air- 
space above it to lift the boat. The work of 
the diver in this case consists of closing hatches 
and bulkhead doors, repairing holes in the 
upper part of the hull, and generally strength- 
ening the deck. It must be remembered that 
a deck is built to take the strain of heavy 
weights bearing down upon it. It is not built 
to be pushed up from beneath, so that frequently 
this method of salving is rendered impractic- 
able because the deck itself cannot stand the 
strain. 

A more common salvage method consists in 
passing cables or chains under the wreck and 
attaching them to large floats or pontoons. 
The slack in the chains is taken up when the tide 
is low, so that on the turn of the tide the wreck 
will be lifted off the bottom. The partially 
raised wreck is then towed into shallower water, 
until it grounds. At the next low tide, the 




Climbing into an Armored Diving.,. Suit 




Lowering an Armored Diver into the Water 







A Diver's Sea Sled ready to be towed along the bed of the sea 




The Sea Sled on Land showing the forward horizontal and 
after vertical rudders 



VICTIMS OF THE SUBMARINE 321 

slack of the chains is again taken in, and at 
flood-tide the wreck is towed nearer land. The 
work proceeds step by step, until the vessel is 
moved inshore far enough to bring its decks 
awash; when it may be patched up and pumped 
out. Where the rise of the tide is not sufficient 
to be of much assistance, hydraulic jacks or 
other lifting-apparatus are used. 

SALVING THE U. S. SUBMARINE F-4 

If the salvor could always be assured of clear 
weather, his troubles would be reduced a hun- 
dredfold, but at best it takes a long time -to 
perform any work dependent upon divers, and 
the chances are very good when they are operat- 
ing in an unsheltered spot, that a storm may 
come up at any time and undo the result of 
weeks and months of labor. This is what 
happened when the submarine F-4 was salved. 
After a month of trying effort the submarine 
was caught in slings hung from barges, lifted 
two hundred and twenty-five feet, and dragged 
within a short distance of the channel entrance 
of the harbor, where the water was but fifty 
feet deep. But just then a violent storm arose, 
which made the barges surge back and forth and 



322 INVENTIONS OF THE GREAT WAR 

plunge so violently that the forward sling cut 
into the plating of the submarine and crushed 
it. The wreck had to be lowered to the bottom 
and the barges cut free to save them from being 
smashed. At the next attempt to raise the F-4 
pontoons were again used, but instead of be- 
ing arranged to float on the surface, they were 
hauled down to the wreck and made fast directly 
to the hull of the submarine. Then when the 
water was forced out of the pontoons with com- 
pressed air, they came up to the surface, bring- 
ing the submarine with them. In this way all 
danger of damage due to sudden storms was 
avoided because water under the surface is not 
disturbed by storms overhead; and when the 
wreck was floated, the pontoons and submarine 
formed a compact unit. 

While this method of salvage seems like a 
very logical one for work in the open sea, one 
is apt to forget how large the pontoons must 
be to lift a vessel of any appreciable size. Not 
only must they support their own dead weight, 
together with that of the sunken vessel, but 
some allowance must usually be made for drag- 
ging the wreck out of the clutches of a sandy or 
muddy bottom. Imagine the work of building 



VICTIMS OF THE SUBMARINE 323 

pontoons large enough to raise the Lusitania, 
They would have to have a combined displace- 
ment greater than that of the vessel itself, and 
they would have to be so large that they would 
be very unwieldy things to handle in a seaway. 
It is for this, reason that submarine pontoons 
are not often used to take the entire weight of 
the vessel. So far they have been employed 
mainly to salve small ships and then only to take 
a portion of the weight, the principal work be- 
ing done by large wrecking-cranes. Instead 
of horizontal pontoons it has been suggested that 
vertical pontoons be employed, so as to provide 
a greater lifting-power without involving the 
use of enormous unwieldy units. 

Ships are not built so that they can be picked 
up by the ends. Such treatment would be lia- 
ble to break their backs in the middle. Were 
they built more like a bridge truss, the salvor's 
difficulties would be materially lessened. It 
would be a much simpler matter to raise a ves- 
sel with pontoons were it so constructed that 
the chains of the pontoon could be attached to 
each end of the hull. But because a ship is 
built to be supported by the water uniformly 
throughout its length, the salvor must use a 



324 INVENTIONS OF THE GREAT WAR 

large number of chains, properly spaced along 
the hull, so as to distribute the load uniformly 
and see that too much weight does not fall on 
this or that pontoon. 

The main problem, however, is to get hold of 
the wreck and this requires the services of 
divers, so that if there were no other limiting 
factor, the depth to which a diver may penetrate 
and perform his duties sets the mark beyond 
which salvage as now conducted is impossible. 

A common diver's suit does not protect the 
diver from hydraulic pressure. Only a flexible 
suit and a thin layer of air separates him from 
the surrounding water. Tins air must neces- 
sarily be of the same pressure as the surround- 
ing water. The air that is pumped down 
to the diver not only serves to supply his 
lungs, but by entering his blood transmits its 
pressure to every part of his anatomy. As 
long as the external pressure is equalized by 
a corresponding pressure within him, the diver 
experiences no serious discomfort. In fact, 
when the pressure is not excessively high he 
finds it rather exhilarating to work under such 
conditions; for, with every breath, he takes 
in an abnormal amount of oxygen. When 




Film Service 
The Diving Sphere built for Deep Sea Salvage Operations 



VICTIMS OF THE SUBMARINE 325 

he returns to the surface he realizes that 
he has been working under forced draft. He 
is very much exhausted and he is very hungry. 
It takes a comparatively short time to build 
up the high internal pressure, which the diver 
must have in order to withstand the pressure of 
the water outside, but it is the decompression 
when he returns to the surface that is attended 
with great discomfort and positive danger. If 
the decompression is not properly effected, the 
diver will sutler agonies and even death from 
the so-called " Caisson Disease.' ' 

A HUMAN SODA-WATEE BOTTLE 

We know now a great deal more than we 
used to know about the effect of compressed 
air on the human system, and because of this 
knowledge divers have recently descended to 
depths undreamed of a few years ago. When 
a diver breathes compressed air, the oxygen is 
largely consumed and exhaled from the lungs 
in the form of carbon-dioxide, but much of the 
nitrogen is dissolved in the blood and does not 
escape. However, like a bottle of soda-water, 
the blood shows no sign of the presence of the 
gas as long as the pressure is maintained. But 



326 INVENTIONS OF THE GREAT WAR 

on a sudden removal of the pressure, the blood 
turns into a froth of nitrogen bubbles, just as 
the soda-water froths when the stopper of the 
bottle is removed. This froth interrupts the 
circulation. The release of pressure is felt 
first in the arteries and large veins. It takes 
some time to reach all the tiny veins, and serious 
differences of pressure are apt to occur that 
often result in the rupture of blood-ves- 
sels. The griping pains that accompany the 
* ' Caisson Disease ' ' are excruciating. The only 
cure is to restore the blood to its original pres- 
sure by placing the patient in a hospital lock, 
or boiler-like affair, where compressed air may 
be admitted; and then to decompress the air 
very slowly. 

It is possible to relieve the pressure in a 
bottle of soda-water so gradually that the gas 
will pass off without the formation of visible 
bubbles, and that is what is sought in decom- 
pressing a diver. After careful research it has 
been found that the pressure may be cut down 
very quickly to half or even less of the original 
amount, but then the diver must wait for the 
decompression to extend to the innermost re- 



VICTIMS OF THE SUBMARINE 327 

cesses of his being and to all the tiny capillaries 
of his venous system. 

In the salvage of the F-4 a diver went down 
306 feet, and remained on the bottom half an 
hour. The pressure upon him was 135 pounds 
per square inch, or about 145 tons on the surface 
of his entire body. Some idea of what this 
means may be gained if we consider that the 
tallest office building in the world does not bear 
on its foundations with a greater weight than 
215 pounds to the square inch or only about 50 
per cent more than the crushing pressure this 
diver had to endure. 

It took the diver a very short time to go down. 
On coming up he proceeded comparatively 
rapidly until he reached a depth of 100 feet. 
There he found the bottom rung of a rope 
ladder. On it he was obliged to rest for several 
minutes before proceeding to the next rung. 
The rungs of this ladder were 10 feet apart, and 
on each rung the diver had to rest a certain 
length of time, according to a schedule that had 
been carefully worked out. At the top rung, 
for instance, only 10 feet from the surface, he 
was obliged to wait forty minutes. In all, it 



328 INVENTIONS OF THE GREAT WAR 

took him an hour and forty-five minutes to come 
up to the surface. The decompression was 
complete and he -suffered no symptoms of the 
"Caisson Disease.' ' But he was so exhausted 
from his efforts that he was unfit for work for 
several days. Yet the operations that he per- 
formed at the depth of 300 feet would not have 
taken more than a few minutes on the surface. 

A SUBMARINE BEST-CHAMBER 

The Germans have paid a great deal of atten- 
tion to deep-diving operations, and no doubt 
while their U-boats were sinking merchant ships 
German salvors were anticipating rich harvests 
after hostilities ended. One scheme they 
developed was a submarine rest-chamber which 
could be permanently located on the bottom of 
the sea close to the point where the salvage 
operations were to take place. This chamber 
consists of a large steel box which is supplied 
with air from the surface and in which divers 
may make themselves comfortable when they 
need a rest after arduous work. Entrance to 
the chamber is effected through a door in the 
floor. The pressure of the air inside prevents 
the water from rising into the chamber and 



VICTIMS OF THE SUBMARINE 329 

flooding it. From this submarine base the 
divers may go out to the wreck, either equipped 
with the ordinary air-tube helmets or with self- 
regenerating apparatus which makes them in- 
dependent of an air-supply for a considerable 
period of time. When the diver has worked for 
an hour or two, or when he is tired, he may re- 
turn to this chamber, remove his helmet, eat a 
hearty meal, take a nap if he needs it, and then 
return to the salvage work without going 
through the exhausting operation of decom- 
pressing. 

CUTTING METAL UNDEK WATEK WITH 
A TOKCH 

The work of the diver usually consists of far 
more than merely passing lines under a sunken 
hull. It is constantly necessary for him to cut 
away obstructing parts.. He- must sometimes 
use blasting-power. Pneumatic cutting-tools 
frequently come into play, but the Germans have 
lately devised an oxy-hydrogen torch for under- 
water use, with which the diver can cut metal 
by burning through it. This is accomplished 
by using a cup-shaped nozzle through which a 
blast of air is projected under such pressure 



330 INVENTIONS OF THE GREAT WAB 

that it blows away the water over the part to be 
cut. The oxygen and hydrogen jets are then 
ignited electrically, and the work of cutting the 
metal proceeds in the hole in the water made by 
the air-blast. A similar submarine torch has 
recently been developed by an American salvage 
company. It was employed successfully in 
cutting drainage-holes in the bulkheads of the 
St. Paul, which was raised in New York Harbor 
in the summer of 1918. 



The diver's sled is still another interesting 
German invention. It is a sled provided with 
vertical and horizontal rudders, which is towed 
by means of a motor-boat at the surface. The 
diver, seated on the sled, and provided with a 
self-contained diving-suit, can direct the motor- 
boat by telephone and steer his sled up and 
down and wherever he chooses. And so with- 
out any physical exertion, he can explore the 
bottom of the sea and hunt f*or wrecks. 

AKMORED DIVING-SUITS 

From time to time attempts bave been made 
to construct a diver's suit that will not yield 



VICTIMS OF THE SUBMARINE 33l 

to the pressure of the sea, so that the diver will 
not be subjected to the weight of the water 
about him, but can breathe air at ordinary 
atmospheric pressure. Curious armor of steel 
has been devised, with articulated arms and 
legs, in which the diver is completely encased. 
With the ordinary rubber suit, the diver usually 
has his hands bare, because he is almost as de- 
pendent upon the sense of touch as a blind man. 
But where the pressure mounts up to such a 
high degree that a metal suit must be used, no 
part of the body may be exposed. If a bare 
hand were extended out of the protecting armor 
it would immediately be mashed into a pulp and 
forced back through the opening in the arms of 
the suit. The best that can be done, then, is 
to furnish the arms of the suit with hooks or 
tongs or other mechanical substitutes for hands 
which will enable the diver to make fast to the 
wreck or various parts of it. 

But if a diver feels helpless in the bag of a 
suit now commonly worn, what would he do 
when encased in a steel boiler; for that is 
virtually what the armored suit is ! A common 
mistake that inventors of armor units have 
made is to fail to consider the effects of the 



332 INVENTIONS OF THE GREAT WAR 

enormous hydraulic pressure on the joints of 
the suit. In order to make them perfectly tight, 
packings* must be employed, and these are liable 
to be so jammed by the hydraulic pressure that 
it is well nigh impossible to articulate the limbs. 
Again, the construction of the suit should be 
such that when a limb is flexed it would not dis- 
place any more water than when in an extended 
position, and vice versa. A diver may find that 
he cannot bend his arm, because in doing so he 
would expand the cubical content of his armor 
by a few cubic inches, and to make room for this 
increment of volume it would be necessary for 
him to lift several hundred pounds of water. 
The hydraulic pressure will reduce the steel suit 
to its smallest possible dimensions, which may 
result either in doubling up the members or ex- 
tending them rigidly. 

But these difficulties are not insuperable. 
There is no reason why a steel manikin cannot 
be constructed with a man inside to direct its 
movements. 



Other schemes have been devised to relieve 
the diver of abnormally high air-pressure. 



VICTIMS OF THE SUBMARINE 333 

One plan is to construct a large spherical work- 
ing-chamber strong enough to withstand any 
hydraulic pressure that might be encountered. 
This working-chamber is equipped with heavy 
glass ports through which the workers can ob- 
serve their surroundings in the light of an 
electric search-light controlled from within the 
chamber. The sphere is to be lowered to the 
wreck from a barge, with which it will be in tele- 
phonic communication and from which it will be 
supplied with electric current to operate various 
electrically driven mechanisms. By means of 
electromagnets this sphere may be made fast to 
the steel hull of the vessel and thereupon an 
electric drill is 'operated to bore a hole in the 
ship and insert the hook of a hoisting-chain. 
This done, the sphere would be moved to an- 
other position, as directed by telephone and an- 
other chain made fast. The hoisting-chains are 
secured to sunken pontoons and after enough 
of the chains have been attached to the wreck 
the pontoons are pumped out and the wreck is 
raised. 

It is a pity that ship-builders have not had 
the forethought to provide substantial shackles 
at frequent intervals firmly secured to the fram- 



334 INVENTIONS OF THE GREAT WAR 

ing. A sunken vessel is really a very difficult 
object to make fast to and the Patent Office 
has recorded many very fantastic schemes for 
getting hold of a ship's hull without the use of 
divers. One man proposes the use of a gigantic 
pair of ice-tongs; and there have been no end 
of suggestions that lifting-magnets be em- 
ployed, but no one who has any idea of how 
large and how heavy such magnets must be 
would give these suggestions any serious consid- 
eration. 

But, after all, the chief obstacle to salvage in 
the open sea is the danger of storms ; months of 
preparation and thousands of dollars' worth of 
equipment may be wiped out in a moment. 

FIGHTING THE WAVES WITH AIR 

However, there has been another recent de- 
velopment which may have a very important 
bearing on this problem of deep-sea salvage 
work. It has often been observed that a sub- 
merged reef, twenty or thirty feet below the 
surface, may act as a breakwater to stop the 
storming waves. An inventor who studied this 
phenomenon arrived at the theory that the 
reefs set up eddies in the water which break 



VICTIMS OF THE SUBMARINE 335 

up the rhythm of the waves and convert them 
into a smother of foam jnst above the reef. 
Thereupon he conceived the idea of performing 
the same work by means of compressed air. He 
laid a pipe on the sea bottom, forty or fifty 
feet below the surface, and pumped air through 
it. Just as he had expected, the line of air 
bubbles produced exactly the same effect as the 
submerged reef. They set up a vertical current 
of water which broke up the waves as soon as 
they struck this barrier of air. 

The "pneumatic breakwater," as it is called, 
has been tried out on an exposed part of the 
California coast, to protect a long pier used by 
an oil company. It has proved so satisfactory 
that the same company has now constructed a 
second breakwater about another pier near by. 
There is no reason why a breakwater of this 
sort should not be made about a wreck to protect 
the workers from storms. Where the water is 
very deep, it would not be necessary to lay the 
compressed-air pipe on the bottom, but it could 
be carried by buoys at a convenient depth. 

Summing up the situation, then, there are 
two serious bars to the successful salvage of 
ships sunk in the open sea — the wild fury of the 



336 INVENTIONS OF THE GREAT WAR 

waves on the surface; and the silent, remorse- 
less pressure of the deep. The former is the 
more to be feared ; and if the waves really can 
be calmed, considerably more than half the 
problem is solved. As for the pressure of the 
sea, it can be overcome, as we have seen, either 
by the use of special submarine mechanisms, 
or of man-operated manikins or even of un- 
armored divers. We have reached a very in- 
teresting stage in the science of salvage, with 
the promise of important developments. Fifty 
fathoms no longer seems a hopeless depth. 

Even in times of peace the sea exacts a dread- 
ful toll of lives and property. Before the war 
the annual loss by shipwreck around the British 
Isles alone was estimated at forty-five million 
dollars. But the war, although it was fright- 
fully destructive to shipping, may in the long 
run save more vessels than it sank; for it has 
given us sound-detectors which should remove 
the danger of collisions in foggy weather, and 
the wireless compass, which should keep ships 
from running off the course and on the rocks. 
And now, if salvage engineering develops as it 
should, the sea will be made to give up not only 



VICTIMS OF THE SUBMARINE 337 

much of the wealth it swallowed during the war, 
but also many of the rich cargoes of gold and 
silver it has been hoarding since the days of the 
Spanish galleon. 



INDEX 



Air, fighting waves, 334 

raising ship, on, 319 

war in, 123 
Airplane, ambulance, 146 

armored, 139 

artillery spotting, 131 

camera, 173 

cartridges, 131 

classes of work, 127 

fighting among clouds, 137 

flying boats, 144 

gasolene tank, 130 

giant, 132 

hospital, 146 

launching from ship, 303 

Liberty motor, 142 

scouting, 125 

scouts, 128 

speed of, 134 

spotting, 177 

training spotters, 180 

wireless telephone, 194 

See also Seaplane 
Ambulance airplane, 146 
Armored diving-suit, 330 
Arms and armor, 111 
Artillery, hand, 23 
Atmosphere, shooting beyond, 

64 
Audion, 185 

Balloon, Blimp, 260 
helium, 164 
historical, 148 
hydrogen, 150 



Balloon, kite, 174 

principles, 150 

record flight, 65 
Barbed wire, 15 

cylinders, 17 

gate, trench, 9 

gates through, 15 

shelling, 16 
Barge for towing seaplanes, 

302 
Barrage, grenade, 27 

mine, 292 
Battle-fields, miniature, 180 
Blimp, 260 

Blisters on ships, 307 , 
Boats, electric, 308 

Eagle, 301 

flying, 144 

surface, 298 
Bombs to destroy barbed 

wire, 16 
Breakwater, pneumatic, 335 
Browning, John M., 56 
Buildings, shadowless, 227 

Caisson disease, 325 
Caliber, 68 

Camera, airplane, 173 
Camouflage and camoufleurs, 
211 

buildings, 227 

grass, 229 

horse, 223 

land, 222 

roads, 225 



339 



340 



INDEX 



Camouflage, ships, 211 

Cartridges, aircraft guns, 131 

Catapults, 36 

Caterpillar tractor, 109 

Caves, 8 

Coffer-dam, salvage, 318 

Color, analyzing, 229 

screens, 229 
Compass, wireless, 201 
Convoy, 267 
Countermines, 17 

Deep sea, conditions in, 312 
Deep water diving, 327 
Depth bombs, 265 
Devil's eggs, 276 
Diesel engine, 240 
Direction-finder, 205 
Dirigible, see Balloon 
Disease, caisson, 325 
Diver, armored suit, 330 

caisson disease, 325 

rest chamber, 328 

sled, 330 

submarine torch, 329 

suit, 324 
Diving, deep, 324 

record depth, 327 
Duck-boards, 9 
Dugouts, 7 

Dummy heads of papier 
mach6, 13 

Eagle boats, 301 
Egg-laying submarines, 287 
Eggs, Devil's, 276 
Electric motor-boat, 308 
Engine, Diesel, 240 

Field-guns, 81 
Fire broom, 105 
liquid, 103 



Forts, machine-gun, 58 
Fuse, grenade, 28 

Gas, 85 

American, 102 
Gas attack, boomerang, 92 

first, 89 
Gas, chlorine, 87 

diphosgene, 96 

exterminating rats, 94 

grenades, 26 

helium, 164 

hydrogen, 150 

lock, 97 

masks, 99 

mustard, 98 

phosgene, 93 

pouring like water, 86 

shell, 95 

sneezing, 98 

tear, 95 

vomiting, 98 
Gasolene-tank, airplane, 130 
Gate, barbed wire, trench, 9 
Gates through barbed wire, 

15 
Gatling gun, 43 
Geologists, Messines Ridge, 19 
Glass, non-shattering, 100 
Grapnel shell, 16 
Graveyard, submarine, 314 
Grenade, disk-shaped, 33 

fuse, 28 

gas, 26 

hair brush, 34 

history of, 23 

Mills, 29 

parachute, 31 

range of, 25 

rifle, 28 

throwing implement, 27 



INDEX 



341 



Grenade, wind-vane safety de- 
vice, 32 
Gun, aircraft, 131 

American, 50-mile, 63 

big, hiding, 226 

caliber, 68 

disappearing, 77 

double-end, 145 

18-inch, monitors, 306 

elastic, 73 

field, 81 

42-centimeter, 79 

how made, 76 

120-mile, 70 

long range, German, 62 

non-recoil, 145 

on submarine, 249 

16-inch, coast defense, 78 

Skoda, 81 

spotting by sound, 181 

three-second life, 73 

12-inch, submarine, 251 

wavs of increasing range, 
67 

wire- wound, 76 

Hand-grenade, see Grenade 
Helium, 164 
Hospital, airplane, 147 
Horizon, seeing beyond, 219 
Howitzer, 79 
Hush ships, 304 
Hydroaeroplanes, see Sea- 
planes 
Hydrogen, weight of, 150 
Hydrophone, 270 

Illusions, optical, 215 

Kilometer, length in miles, 6 
Kite balloons, 174 
Kite, water, 283 



Liberty motor, 142 
Liquid'-fire, 103 
Locomotives, gasolene, 10 
Liositania, 316 

Machine-gun, 112 

airplane, 127 

Benet-Mercie, 52 

Browning, 53 

Colt, 44 

forts, 58 

Gatling, 43 

history, 41 

Hotchkiss, 49 

Lewis, 50 

Maxim, 42 

water-jacket, 47 

worth in rifles, 58 
Machine-rifle, 55 
Magnets, lifting, salvage, 334 
Maps, making with camera, 

175 
Marne, first battle of, 4 
Messines Ridge, mine, 19 
Metal-cutting under water, 

329 
Microphone detectors, mines, 

18 
Mine-field, North Sea, 290 
Mine laying, North Sea, 292 
Mine-laying submarine, 287 
Mine railroad, 294 
Mine-sweeping, 281 
Mines, 276 

anchored, 278 

and countermines, 17 

automatic sounding, 278 

drift of, 285 

electric, 277 

floating, 284 

Messines Ridge, 19 



342 



INDEX 



Mines, paravanes, 288 
Monitors, 306 
Mortars, 79 

depth bomb, 266 

flying, 23 
Mortars, See also Trench 

mortars 
Mother-ships for airplanes, 

305 
Motor-boat, electric, 308 

sea Tank, 299 
Motor torpedo-boats, 298 
Mystery ships, 220 

Net, North Sea, 290 

Ocean currents, 285 
Optical illusions, 215 
Oxy-hydrogen torch, subma- 
rine, 329 

Paint in war, 209 
Papier mache - heads, 13 
Papier mache - horse, 223 
Parachute, 175 

grenade, 31 

searchlight shell, 84 
Paravanes, 288 
Periscope, submarine, 244 

trench, 11 
Pill-boxes, 59 

Pneumatic breakwater, 335 
Pontoons, salvage, 320 
Propeller, shooting through, 
136 

Radio, see Wireless 
Railroad, mine, 294 
Railways, trench, 10 
Range-finder, 170 
Range, getting the, 169 



Range of guns, increasing, 67 
Range, torpedo, 213 
Rats, freeing trenches of, 94 
Rifle grenade, 28 

safety device, 32 
Rifle, machine, 55 
Rifle stand, fixed, 14 
Roads, camouflage, 225 

Salvage, 310 

diving, 324 

ice-tongs, 334 

lifting-magnets, 334 

methods, 317 

pneumatic, 319 

pontoons, 320 

shackles on ships, 333 

submarine F-4, 321 

submarine sphere, 332 
Scouts, airplane, 128 
Sea, deep, conditions, 312 
Sea gulls finding submarines, 

258 
Sea lions locating submarines, 

259 
Sea tank, 299 
Seaplane, 143 

automatic, 145 

submarine patrol, 259 

torpedo, 145 

towing-barges, 302 
Search-light shell, 84 
Shackles, salvage, 333 
Shadowless buildings, 227 
Shell, gas, 95 

grapnel, 16 

search-light, 84 

shrapnel, 83 

Stokes mortar, 39 
Shield on wheels, 114 
Ships, airplane, 304 



INDEX 



343 



Ships, blisters, 307 

camouflage, 211 

"clothes-line/' 220 

convoy, 267 

hush, 304 

making visible, 230 

monitors, 306 

mystery, 220 

railroads on, 294 
' sunk by submarines, 310 
Ships, see also Salvage 
Shrapnel shell, 83 
Sled, submarine, 330 
Smoke screen, 262 
Sniper, locating, 13 
Sniperscopes, 12 
Sound, detecting submarines, 

269 
Sound detectors, mines, 18 
Sound, spotting by, 181 
Sphere, salvor's submarine, 

332 
Spotting by sound, 181 
Spotting gun-fire, 177 
Submarine, blindness, 244 

chasers, 255 

construction, 234 

depth bombs, 265 

egg-laying, 287 

engines, 246 

F-4, salving, 321 

getting best of, 253 

graveyard, 314 

guns on, 249 

history, 232 

hydrophone, 270 

mine-field, 290 

mine-laying, 287 

net, 290 

oil-tank, 236 

periscope, 244 



Submarine, reclaiming vic- 
tims of, 310 

rest chamber, 328 

salvage vessel, 332 

sea-gulls, 258 

sea-lions, 259 

seaplanes, 259 

ships sunk, 310 

sled, 330 

steam-driven, 250 

torch, 329 

torpedo, 246 

12-inch gun, 251 

vs. submarine, 269 
Super-guns, 62 



Tank, 107 

American, 122 

flying, 139 

French, 119 

German, 120 

one-man, 114 

sea, 299 

small, 121 
Telegraphy, rapid, 199 
Telephone, New York to San 
Francisco, 186 

wireless, 178 
Titanic, 314 

TNT (trinitrotoluol), 18 
Torch, submarine, 329 
Torpedo, 299 

boats, motor, 298 

electrically steered, 308 

construction, 246 

getting range, 213 

proof ships, 306 

seaplane, 145 
Towing-barge, seaplane, 302 
Trajectory, 22 



344 



INDEX 



Trench, gas-lock, 97 
Trench mortar, 36 

pneumatic, 37 

Stokes, 38 
Trench railways, 10 
Trench warfare, 4 
Trenches, 21 

barbed wire gates, 9 

duck-boards, 9 
Tunnels, mines, 17 

to observation posts, 12 

U-boats, see Submarines 

Villages, underground, 7 

Walking-machine, 108 

War, paint, 209 

Water kites, 283 

Waves, fighting with air, 334 



Wireless compass, 201 
spy detector, 200 

Wireless telegraph, rapid, 199 

Wireless telegraphy explained, 
188 

Wireless telephone, 178 
airplane, 184 

Wireless telephony across At- 
lantic, 192 

Woolworth Building, falling 
from, 135 

Wrecks, see Salvage 

Zeppelin and Lowe's balloon, 
149 

Zeppelin balloon, construc- 
tion, 156 

Zeppelin, suspended observer, 
162 

Zeppelin's failures and suc- 
cesses, 154 



33 



7 A 9, 



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